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C Programming Code Examples

C > Games and Graphics Code Examples

A Simple 2D-Drawing Program

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/* A Simple 2D-Drawing Program */ #include<stdio.h> #include<conio.h> #include<graphics.h> #define ESC 0x1b void drcir(int,int,int); void drarc(int,int,int); void main() { int a,b,c,d,e,f,curcolor=3; int gdriver = DETECT,gmode; initgraph(&gdriver,&gmode,"c:\tc\bgi"); verybegin: sound(333); delay(100); sound(222); delay(100); sound(250); delay(100); sound(33); delay(100); sound(111); delay(100); sound(222); delay(100); sound(333); delay(100); sound(3333); delay(100); nosound(); gotoxy(25,1); printf("2d Drawing"); gotoxy(18,5); printf("A Simple Program"); gotoxy(18,6); printf("This is used for drawing circles,arcs,rectangle,"); gotoxy(18,7); printf("lines and many more..."); printf(" The Controls For The Two-Dimensional Drawing "); printf(" N(Up Arrow) = North "); printf(" S(Down Arrow) = South "); printf(" E(Right Arrow) = East "); printf(" W(Left Arrow) = West "); printf(" F(Page Up) = North-East "); printf(" X(Home) = North-West "); printf(" D(Page Down) = South-East "); printf(" Z(End) = South-West "); printf(" J = Current Position "); printf(" B = Help(This Screen) "); printf(" R(Insert) = Reset "); printf(" T = Color Change(0-9) "); printf(" C = Circle "); printf(" A = Arc "); printf(" ESC = Quit "); getch(); begin: curcolor=3; a = getmaxx() / 2; b = getmaxy() / 2; cleardevice(); start: putpixel(a,b,curcolor); c=getch(); sound(100); delay(20); nosound(); if(c==ESC) { goto end; } switch(c) { case 'N': case 'n': case 'H': case 'h': c=a; d=b-1; a=c; b=d; goto start; case 'S': case 's': case 'P': case 'p': c=a; d=b+1; a=c; b=d; goto start; case 'E': case 'e': case 'M': case 'm': c=a+1; d=b; a=c; b=d; goto start; case 'W': case 'w': case 'K': case 'k': c=a-1; d=b; a=c; b=d; goto start; case 'D': case 'd': case 'Q': case 'q': c=a+1; d=b+1; a=c; b=d; goto start; case 'X': case 'x': case 'G': case 'g': c=a-1; d=b-1; a=c; b=d; goto start; case 'Z': case 'z': case 'O': case 'o': c=a-1; d=b+1; a=c; b=d; goto start; case 'F': case 'f': case 'I': case 'i': c=a+1; d=b-1; a=c; b=d; goto start; case 'R': case 'r': goto begin; case 'J': case 'j': f=curcolor+1; putpixel(a,b,f); gotoxy(1,2); printf("X=%d,Y=%d",a,b); sound(100); getch(); gotoxy(1,2); printf(" "); nosound(); goto start; case 'C': case 'c': drcir(a,b,curcolor); goto start; case 'A': case 'a': drarc(a,b,curcolor); goto start; case 'T': case 't': gotoxy(1,2); printf("Enter color code:"); e=getche(); curcolor=e; setcolor(curcolor); gotoxy(1,2); printf(" "); goto start; case 'B': case 'b': cleardevice(); goto verybegin; default: goto start; } end: cleardevice(); closegraph(); } void drcir(int x,int y,int ccolor) { int r; gotoxy(1,2); printf("Enter Radius of Circle:"); scanf("%d",&r); gotoxy(1,2); printf(" "); setcolor(ccolor); circle(x,y,r); } void drarc(int x,int y,int ccolor) { int r,sa,ea; gotoxy(1,2); printf("Enter Radius:"); scanf("%d",&r); gotoxy(1,2); printf(" "); gotoxy(1,2); printf("Enter Starting Angle:"); scanf("%d",&sa); gotoxy(1,2); printf(" "); gotoxy(1,2); printf("Enter Ending Angle:"); scanf("%d",&ea); gotoxy(1,2); printf(" "); setcolor(ccolor); arc(x,y,sa,ea,r); }
cleardevice() Function in C
The header file graphics.h contains cleardevice() function. cleardevice() is a function which is used to clear the screen by filling the whole screen with the current background color. It means that cleardevice() function is used to clear the whole screen with the current background color and it also sets the current position to (0,0). . Both clrscr() and cleardevice() functions are used to clear the screen but clrscr() is used in text mode and cleardevice function is used in the graphics mode.
Syntax for cleardevice() Function in C
#include <graphics.h> void cleardevice();
Clearing the screen is always an issue for developers, because now and then we want to show the user some useful or important data, which should be highlighted or at least have user's attention. It is important to note that, after clearing the device, we will lose all our drawing, shapes or images. It is useful but be little cautious.
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/* clear the screen in graphics mode and set the current position to (0,0) by cleardevice() function example.*/ #include <graphics.h> #include <conio.h> int main() { //initilizing graphic driver and //graphic mode variable int graphicdriver=DETECT,graphicmode; //calling initgraph initgraph(&graphicdriver,&graphicmode,"c:\\turboc3\\bgi"); //Printing message for user outtextxy(20, 20 + 20, "Program to use graph default in C graphics"); //message to clear screen outtextxy(20, 50 + 30, "Press any key to clear screen"); //getting character and clear the device screen getch(); cleardevice(); //message to press key to get exit from program outtextxy(20, 20 + 20, "Press any key to exit..."); getch(); return 0; }
circle() Function in C
This library function is declared in graphics.h and used to draw a circle; it takes centre point coordinates and radius. Circle function is used to draw a circle with center (x,y) and third parameter specifies the radius of the circle. The code given below draws a circle. Where, (x, y) is center of the circle. 'radius' is the Radius of the circle.
Syntax for circle() Function in C
#include <graphics.h> circle(x, y, radius);
x
X-coordinate of the circle
y
Y-coordinate of the circle
radius
radius of the circle This function does not return any value.
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/* draw a circle with center at (x, y) and given radius by circle() function example. */ // C Implementation for drawing circle #include <graphics.h> //driver code int main() { // gm is Graphics mode which is // a computer display mode that // generates image using pixels. // DETECT is a macro defined in // "graphics.h" header file int gd = DETECT, gm; // initgraph initializes the // graphics system by loading a // graphics driver from disk initgraph(&gd, &gm, ""); // circle function circle(250, 200, 50); getch(); // closegraph function closes the // graphics mode and deallocates // all memory allocated by // graphics system . closegraph(); return 0; }
Goto Statement in C
A goto statement in C programming language provides an unconditional jump from the 'goto' to a labeled statement in the same function. The goto statement is known as jump statement in C. As the name suggests, goto is used to transfer the program control to a predefined label. The goto statment can be used to repeat some part of the code for a particular condition. It can also be used to break the multiple loops which can't be done by using a single break statement.
Syntax for Goto Statement in C
label: //some part of the code; goto label;
Use of goto statement is highly discouraged in any programming language because it makes difficult to trace the control flow of a program, making the program hard to understand and hard to modify. Any program that uses a goto can be rewritten to avoid them.
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/* transfer control of the program to the specified label by goto statement example */ // Program to calculate the sum and average of positive numbers // If the user enters a negative number, the sum and average are displayed. #include <stdio.h> int main() { const int maxInput = 100; int i; double number, average, sum = 0.0; for (i = 1; i <= maxInput; ++i) { printf("%d. Enter a number: ", i); scanf("%lf", &number); // go to jump if the user enters a negative number if (number < 0.0) { goto jump; } sum += number; } jump: average = sum / (i - 1); printf("Sum = %.2f\n", sum); printf("Average = %.2f", average); return 0; }
#include Directive in C
#include is a way of including a standard or user-defined file in the program and is mostly written at the beginning of any C/C++ program. This directive is read by the preprocessor and orders it to insert the content of a user-defined or system header file into the following program. These files are mainly imported from an outside source into the current program. The process of importing such files that might be system-defined or user-defined is known as File Inclusion. This type of preprocessor directive tells the compiler to include a file in the source code program. Here are the two types of file that can be included using #include: • Header File or Standard files: This is a file which contains C/C++ function declarations and macro definitions to be shared between several source files. Functions like the printf(), scanf(), cout, cin and various other input-output or other standard functions are contained within different header files. So to utilise those functions, the users need to import a few header files which define the required functions. • User-defined files: These files resembles the header files, except for the fact that they are written and defined by the user itself. This saves the user from writing a particular function multiple times. Once a user-defined file is written, it can be imported anywhere in the program using the #include preprocessor.
Syntax for #include Directive in C
#include "user-defined_file"
Including using " ": When using the double quotes(" "), the preprocessor access the current directory in which the source "header_file" is located. This type is mainly used to access any header files of the user's program or user-defined files.
#include <header_file>
Including using <>: While importing file using angular brackets(<>), the the preprocessor uses a predetermined directory path to access the file. It is mainly used to access system header files located in the standard system directories.
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/* #include directive tells the preprocessor to insert the contents of another file into the source code at the point where the #include directive is found. */ // C program to illustrate file inclusion // <> used to import system header file #include <stdio.h> // " " used to import user-defined file #include "process.h" // main function int main() { // add function defined in process.h add(10, 20); // mult function defined in process.h multiply(10, 20); // printf defined in stdio.h printf("Process completed"); return 0; }
If Else Statement in C
The if-else statement is used to perform two operations for a single condition. The if-else statement is an extension to the if statement using which, we can perform two different operations, i.e., one is for the correctness of that condition, and the other is for the incorrectness of the condition. Here, we must notice that if and else block cannot be executed simiulteneously. Using if-else statement is always preferable since it always invokes an otherwise case with every if condition.
Syntax for if-else Statement in C
if (test expression) { // run code if test expression is true } else { // run code if test expression is false }
If the test expression is evaluated to true, • statements inside the body of if are executed. • statements inside the body of else are skipped from execution. If the test expression is evaluated to false, • statements inside the body of else are executed • statements inside the body of if are skipped from execution.
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/* if else statement in C language */ // Check whether an integer is odd or even #include <stdio.h> int main() { int number; printf("Enter an integer: "); scanf("%d", &number); // True if the remainder is 0 if (number%2 == 0) { printf("%d is an even integer.",number); } else { printf("%d is an odd integer.",number); } return 0; }
initgraph() Function in C
initgraph initializes the graphics system by loading a graphics driver from disk (or validating a registered driver), and putting the system into graphics mode. To start the graphics system, first call the initgraph function. initgraph loads the graphics driver and puts the system into graphics mode. You can tell initgraph to use a particular graphics driver and mode, or to autodetect the attached video adapter at run time and pick the corresponding driver. If you tell initgraph to autodetect, it calls detectgraph to select a graphics driver and mode. initgraph also resets all graphics settings to their defaults (current position, palette, color, viewport, and so on) and resets graphresult to 0. Normally, initgraph loads a graphics driver by allocating memory for the driver (through _graphgetmem), then loading the appropriate .BGI file from disk. As an alternative to this dynamic loading scheme, you can link a graphics driver file (or several of them) directly into your executable program file.
Syntax for initgraph() Function in C
#include <graphics.h> void initgraph(int *graphdriver, int *graphmode, char *pathtodriver);
pathtodriver
pathtodriver specifies the directory path where initgraph looks for graphics drivers. initgraph first looks in the path specified in pathtodriver, then (if they are not there) in the current directory. Accordingly, if pathtodriver is null, the driver files (*.BGI) must be in the current directory. This is also the path settextstyle searches for the stroked character font files (*.CHR).
graphdriver
graphdriver is an integer that specifies the graphics driver to be used. You can give it a value using a constant of the graphics_drivers enumeration type, which is defined in graphics.h and listed below. • DETECT – 0 (requests autodetect) • CGA – 1 • MCGA – 2 • EGA – 3 • EGA64 – 4 • EGAMONO – 5 • IBM8514 – 6 • HERCMONO – 7 • ATT400 – 8 • VGA – 9 • PC3270 – 10
graphmode
graphmode is an integer that specifies the initial graphics mode (unless *graphdriver equals DETECT; in which case, *graphmode is set by initgraph to the highest resolution available for the detected driver). You can give *graphmode a value using a constant of the graphics_modes enumeration type, which is defined in graphics.h and listed below. initgraph always sets the internal error code; on success, it sets the code to 0. If an error occurred, *graphdriver is set to -2, -3, -4, or -5, and graphresult returns the same value as listed below: • grNotDetected: -2 Cannot detect a graphics card • grFileNotFound: -3 Cannot find driver file • grInvalidDriver: -4 Invalid driver • grNoLoadMem: -5 Insufficient memory to load driver
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/* initgraph initializes the graphics system by loading a graphics driver by initgraph() function example*/ #include <graphics.h> #include <stdlib.h> #include <stdio.h> #include <conio.h> int main(void) { /* request auto detection */ int gdriver = DETECT, gmode, errorcode; /* initialize graphics mode */ initgraph(&gdriver, &gmode, ""); /* read result of initialization */ errorcode = graphresult(); if (errorcode != grOk) /* an error occurred */ { printf("Graphics error: %s\n", grapherrormsg(errorcode)); printf("Press any key to halt:"); getch(); exit(1); /* return with error code */ } /* draw a line */ line(0, 0, getmaxx(), getmaxy()); /* clean up */ getch(); closegraph(); return 0; }
gotoxy() Function in C
The gotoxy() function places the cursor at the desired location on the screen. This means it is possible to change the cursor location on the screen using the gotoxy() function. It is basically used to print text wherever the cursor is moved.
Syntax for gotoxy() Function in C
#include <stdio.h> void gotoxy(int x, int y);
x
x-coordinate of the point
y
y-coordinate of the point where (x, y) is the position where we want to place the cursor. If you want to take your cursor on a particular coordinate on the window, then this function is made for you. What it takes from you are two parameters. The Integers should be the x and y coordinate of the console. This is pretty helpful for games and animations. The Integers should be passed when you call the function in your program.
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/* place cursor at a desired location on screen by gotoxy() function example */ #include <stdio.h> //to use 'gotoxy()' and 'getch()' #include <conio.h> int main() { // define the type of variables int a, b; // define the value of variables a = 50; b = 30; // change cursor position on further co-ordinates. gotoxy(a, b); // message printf("The position of cursor is changed"); // for killing the execution getch(); return 0; }
#define Directive in C
In the C Programming Language, the #define directive allows the definition of macros within your source code. These macro definitions allow constant values to be declared for use throughout your code. Macro definitions are not variables and cannot be changed by your program code like variables. You generally use this syntax when creating constants that represent numbers, strings or expressions.
Syntax for #define Directive in C
#define NAME value /* this syntax creates a constant using define*/ // Or #define NAME (expression) /* this syntax creates a constant using define*/
NAME
is the name of a particular constant. It can either be defined in smaller case or upper case or both. Most of the developers prefer the constant names to be in the upper case to find the differences.
value
defines the value of the constant.
Expression
is the value that is assigned to that constant which is defined. The expression should always be enclosed within the brackets if it has any operators. In the C programming language, the preprocessor directive acts an important role within which the #define directive is present that is used to define the constant or the micro substitution. The #define directive can use any of the basic data types present in the C standard. The #define preprocessor directive lets a programmer or a developer define the macros within the source code. This macro definition will allow the constant value that should be declared for the usage. Macro definitions cannot be changed within the program's code as one does with other variables, as macros are not variables. The #define is usually used in syntax that created a constant that is used to represent numbers, strings, or other expressions. The #define directive should not be enclosed with the semicolon(;). It is a common mistake done, and one should always treat this directive as any other header file. Enclosing it with a semicolon will generate an error. The #define creates a macro, which is in association with an identifier or is parameterized identifier along with a token string. After the macro is defined, then the compiler can substitute the token string for each occurrence of the identifier within the source file.
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/* #define directive allows the definition of macros within your source code. These macro definitions allow constant values to be declared for use throughout your code. */ #include <stdio.h> #include <string.h> typedef struct Books { char title[50]; char author[50]; char subject[100]; int book_id; } Book; int main( ) { Book book; strcpy( book.title, "C Programming"); strcpy( book.author, "XCoder"); strcpy( book.subject, "C Programming Tutorial"); book.book_id = 6495407; printf( "Book title : %s\n", book.title); printf( "Book author : %s\n", book.author); printf( "Book subject : %s\n", book.subject); printf( "Book book_id : %d\n", book.book_id); return 0; }
sound() Function in C
Our system can create various sounds on different frequencies. The sound() is very useful as it can create very nice music with the help of programming and our user can enjoy music during working in out the program. Sound function produces the sound of a specified frequency. Used for adding music to a C program, try to use some random values in loop, vary delay and enjoy.
Syntax for sound() Function in C
#include <dos.h> void sound(unsigned frequency);
The delay() function has been used in this function to delay for the next sound. The Second thing is the nosound() function, which simply silent the system. These two functions are from file dos.h, which should be included in the program.
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/* produce the sound of a specified frequency by sound() function example */ #include <stdio.h> //to use 'sound()', 'delay()' functions #include <dos.h> int main() { //calling the function for producing //the sound of frequency 400. sound(400); //function to delay the sound for //half of second. delay(500); //the sound of frequency 200. sound(200); //the sound of frequency 500. sound(500); //calling the function to stop the //system sound. nosound(); return 0; }
getmaxx() Function in C
The header file graphics.h contains getmaxx() function which returns the maximum X coordinate for current graphics mode and driver. getmaxx() returns the maximum (screen-relative) x value for the current graphics driver and mode. For example, on a CGA in 320*200 mode, getmaxx returns 319. getmaxx is invaluable for centering, determining the boundaries of a region onscreen, and so on.
Syntax for getmaxx() Function in C
#include <graphics.h> int getmaxx(void);
getmaxx returns the maximum x screen coordinate. getmaxx() function is used to fetch the maximum X coordinate for the current graphics mode or driver.
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/* get the maximum X coordinate for current graphics mode and driver by getmaxx() function code example */ #include <graphics.h> #include <stdio.h> // driver code int main() { // gm is Graphics mode which is // a computer display mode that // generates image using pixels. // DETECT is a macro defined in // "graphics.h" header file int gd = DETECT, gm; char arr[100]; // initgraph initializes the // graphics system by loading a // graphics driver from disk initgraph(&gd, &gm, ""); // sprintf stands for "String print". // Instead of printing on console, it // store output on char buffer which // are specified in sprintf sprintf(arr, "Maximum X coordinate for current " "graphics mode And driver = %d", getmaxx()); // outtext function displays text at // current position. outtext(arr); getch(); // closegraph function closes the // graphics mode and deallocates // all memory allocated by // graphics system . closegraph(); return 0; }
nosound() Function in C
The nosound() function in C language is used to stop the sound played by sound() function. nosound() function is simply silent the system. Sound function produces the sound of a specified frequency and nosound function turn off the PC speaker.
Syntax for nosound() Function in C
#include <dos.h> void nosound();
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/* silent the system by nosound() function example */ #include <stdio.h> //to use 'sound()', 'delay()' functions #include <dos.h> int main() { //calling the function for producing //the sound of frequency 400. sound(400); //function to delay the sound for //half of second. delay(500); //calling the function for producing //the sound of frequency 250. sound(250); //function to delay the sound for //half of second. delay(500); //calling the function to stop the //system sound. nosound(); return 0; }
putpixel() Function in C
putpixel() plots a point in the color defined by color at (x,y). The header file graphics.h contains putpixel() function which plots a pixel at location (x, y) of specified color. Where, (x, y) is the location at which pixel is to be put, and color specifies the color of the pixel.
Syntax for putpixel() Function in C
#include <graphics.h> void putpixel(int x, int y, int color);
x
X coordinate of the point
y
Y coordinate of the point
color
specifies the color of the pixel To put a pixel on the screen at a particular position, calling the pixel() function is a good way. This function takes three parameters as the position of the pixel and also the color of the pixel. To use these function in your program, we would need to include graphics.h file in your program. You should also use getch() function to make the screen freeze.
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/* plot a pixel at location (x, y) of specified color by putpixel() function code example */ #include <graphics.h> #include <stdio.h> // driver code int main() { // gm is Graphics mode which is // a computer display mode that // generates image using pixels. // DETECT is a macro defined in // "graphics.h" header file int gd = DETECT, gm, color; // initgraph initializes the // graphics system by loading a // graphics driver from disk initgraph(&gd, &gm, ""); // putpixel function putpixel(85, 35, GREEN); putpixel(30, 40, RED); putpixel(115, 50, YELLOW); putpixel(135, 50, CYAN); putpixel(45, 60, BLUE); putpixel(20, 100, WHITE); putpixel(200, 100, LIGHTBLUE); putpixel(150, 100, LIGHTGREEN); putpixel(200, 50, YELLOW); putpixel(120, 70, RED); getch(); // closegraph function closes the // graphics mode and deallocates // all memory allocated by // graphics system . closegraph(); return 0; }
main() Function in C
In C, the "main" function is treated the same as every function, it has a return type (and in some cases accepts inputs via parameters). The only difference is that the main function is "called" by the operating system when the user runs the program. Thus the main function is always the first code executed when a program starts. main() function is a user defined, body of the function is defined by the programmer or we can say main() is programmer/user implemented function, whose prototype is predefined in the compiler. Hence we can say that main() in c programming is user defined as well as predefined because it's prototype is predefined. main() is a system (compiler) declared function whose defined by the user, which is invoked automatically by the operating system when program is being executed. Its first function or entry point of the program from where program start executed, program's execution starts from the main. So main is an important function in c , c++ programming language.
Syntax for main() Function in C
void main() { ......... // codes start from here ......... }
void
is a keyword in C language, void means nothing, whenever we use void as a function return type then that function nothing return. here main() function no return any value. In place of void we can also use int return type of main() function, at that time main() return integer type value.
main
is a name of function which is predefined function in C library. • An operating system always calls the main() function when a programmers or users execute their programming code. • It is responsible for starting and ends of the program. • It is a universally accepted keyword in programming language and cannot change its meaning and name. • A main() function is a user-defined function in C that means we can pass parameters to the main() function according to the requirement of a program. • A main() function is used to invoke the programming code at the run time, not at the compile time of a program. • A main() function is followed by opening and closing parenthesis brackets.
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/* basic c program by main() function example */ #include <stdio.h> #include <conio.h> main() { printf (" It is a main() function "); int fun2(); // jump to void fun1() function printf ("\n Finally exit from the main() function. "); } void fun1() { printf (" It is a second function. "); printf (" Exit from the void fun1() function. "); } int fun2() { void fun1(); // jump to the int fun1() function printf (" It is a third function. "); printf (" Exit from the int fun2() function. "); return 0; }
scanf() Function in C
Read formatted data from stdin. Reads data from stdin and stores them according to the parameter format into the locations pointed by the additional arguments. The additional arguments should point to already allocated objects of the type specified by their corresponding format specifier within the format string. In C programming, scanf() is one of the commonly used function to take input from the user. The scanf() function reads formatted input from the standard input such as keyboards. The scanf() function enables the programmer to accept formatted inputs to the application or production code. Moreover, by using this function, the users can provide dynamic input values to the application.
Syntax for scanf() Function in C
#include <stdio.h> int scanf ( const char * format, ... );
format
C string that contains a sequence of characters that control how characters extracted from the stream are treated: • Whitespace character: the function will read and ignore any whitespace characters encountered before the next non-whitespace character (whitespace characters include spaces, newline and tab characters -- see isspace). A single whitespace in the format string validates any quantity of whitespace characters extracted from the stream (including none). • Non-whitespace character, except format specifier (%): Any character that is not either a whitespace character (blank, newline or tab) or part of a format specifier (which begin with a % character) causes the function to read the next character from the stream, compare it to this non-whitespace character and if it matches, it is discarded and the function continues with the next character of format. If the character does not match, the function fails, returning and leaving subsequent characters of the stream unread. • Format specifiers: A sequence formed by an initial percentage sign (%) indicates a format specifier, which is used to specify the type and format of the data to be retrieved from the stream and stored into the locations pointed by the additional arguments. A format specifier for scanf follows this prototype: %[*][width][length]specifier
specifier
Where the specifier character at the end is the most significant component, since it defines which characters are extracted, their interpretation and the type of its corresponding argument:
i – integer
Any number of digits, optionally preceded by a sign (+ or -). Decimal digits assumed by default (0-9), but a 0 prefix introduces octal digits (0-7), and 0x hexadecimal digits (0-f). Signed argument.
d or u – decimal integer
Any number of decimal digits (0-9), optionally preceded by a sign (+ or -). d is for a signed argument, and u for an unsigned.
o – octal integer
Any number of octal digits (0-7), optionally preceded by a sign (+ or -). Unsigned argument.
x – hexadecimal integer
Any number of hexadecimal digits (0-9, a-f, A-F), optionally preceded by 0x or 0X, and all optionally preceded by a sign (+ or -). Unsigned argument.
f, e, g – floating point number
A series of decimal digits, optionally containing a decimal point, optionally preceeded by a sign (+ or -) and optionally followed by the e or E character and a decimal integer (or some of the other sequences supported by strtod). Implementations complying with C99 also support hexadecimal floating-point format when preceded by 0x or 0X.
c – character
The next character. If a width other than 1 is specified, the function reads exactly width characters and stores them in the successive locations of the array passed as argument. No null character is appended at the end.
s – string of characters
Any number of non-whitespace characters, stopping at the first whitespace character found. A terminating null character is automatically added at the end of the stored sequence.
p – pointer address
A sequence of characters representing a pointer. The particular format used depends on the system and library implementation, but it is the same as the one used to format %p in fprintf.
[characters] – scanset
Any number of the characters specified between the brackets. A dash (-) that is not the first character may produce non-portable behavior in some library implementations.
[^characters] – negated scanset
Any number of characters none of them specified as characters between the brackets.
n – count
No input is consumed. The number of characters read so far from stdin is stored in the pointed location.
%
A % followed by another % matches a single %. Except for n, at least one character shall be consumed by any specifier. Otherwise the match fails, and the scan ends there.
sub-specifier
The format specifier can also contain sub-specifiers: asterisk (*), width and length (in that order), which are optional and follow these specifications:
*
An optional starting asterisk indicates that the data is to be read from the stream but ignored (i.e. it is not stored in the location pointed by an argument).
width
Specifies the maximum number of characters to be read in the current reading operation (optional).
length
One of hh, h, l, ll, j, z, t, L (optional). This alters the expected type of the storage pointed by the corresponding argument (see below).
... (additional arguments)
Depending on the format string, the function may expect a sequence of additional arguments, each containing a pointer to allocated storage where the interpretation of the extracted characters is stored with the appropriate type. There should be at least as many of these arguments as the number of values stored by the format specifiers. Additional arguments are ignored by the function. These arguments are expected to be pointers: to store the result of a scanf operation on a regular variable, its name should be preceded by the reference operator (&) (see example). On success, the function returns the number of items of the argument list successfully filled. This count can match the expected number of items or be less (even zero) due to a matching failure, a reading error, or the reach of the end-of-file. If a reading error happens or the end-of-file is reached while reading, the proper indicator is set (feof or ferror). And, if either happens before any data could be successfully read, EOF is returned. If an encoding error happens interpreting wide characters, the function sets errno to EILSEQ.
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/* read formatted data from stdin by scanf() function example */ #include <stdio.h> #include <stdlib.h> #include <string.h> int main(int argc, const char * argv[]) { /* Define temporary variables */ char name[10]; int age; int result; /* Ask the user to enter their first name and age */ printf("Please enter your first name and your age.\n"); /* Read a name and age from the user */ result = scanf("%s %d",name, &age); /* We were not able to parse the two required values */ if (result < 2) { /* Display an error and exit */ printf("Either name or age was not entered\n\n"); exit(0); } /* Display the values the user entered */ printf("Name: %s\n", name); printf("Age: %d\n", age); return 0; }
arc() Function in C
In the C programming language, there is an option to create an arc of a circle of a given radius with a given center coordinates and degree of the arc. The arc() function is used to create an arc. This arc function is included in graphics.h library in C which contains methods that can draw figures on the output screen. The function to make an arc(), accepts five parameters for x, y co-ordinate, starting angle, end angle and radius. This will make the arc will all the values are fine. The Example below takes care of all these things as it have four arcs implemented.
Syntax for arc() Function in C
#include <graphics.h> void arc(int x, int y, int start_angle, int end_angle, int radius);
x
x coordinate of the center of the arc
y
y coordinate of the center of the arc
start_angle
starting angle of arc
end_angle
ending angle of arc
radius
radius of the arc The header file graphics.h contains arc() function which draws an arc with center at (x, y) and given radius. start_angle is the starting point of angle and end_angle is the ending point of the angle. The value of the angle can vary from 0 to 360 degree.
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/* create an arc of a circle of a given radius with a given center coordinates and degree of the arc by arc() function code example */ #include <graphics.h> #include <conio.h> int main() { //initilizing graphic driver and //graphic mode variable int graphicdriver=DETECT,graphicmode; //calling initgraph with parameters initgraph(&graphicdriver,&graphicmode,"c:\\turboc3\\bgi"); //Printing message for user outtextxy(10, 10 + 10, "Program to draw arcs of diffrent sizes in C graphics"); // creating arcs using arc function. arc(80, 80, 0, 12, 50); arc(200, 100, 0, 200, 50); arc(300, 100, 0, 240, 50); arc(400, 100, 0, 120, 50); getch(); return 0; }
Switch Case Statement in C
Switch statement in C tests the value of a variable and compares it with multiple cases. Once the case match is found, a block of statements associated with that particular case is executed. Each case in a block of a switch has a different name/number which is referred to as an identifier. The value provided by the user is compared with all the cases inside the switch block until the match is found. If a case match is NOT found, then the default statement is executed, and the control goes out of the switch block.
Syntax for Switch Case Statement in C
switch(expression) { case constant-expression : statement(s); break; /* optional */ case constant-expression : statement(s); break; /* optional */ /* you can have any number of case statements */ default : /* Optional */ statement(s); }
• The expression used in a switch statement must have an integral or enumerated type, or be of a class type in which the class has a single conversion function to an integral or enumerated type. • You can have any number of case statements within a switch. Each case is followed by the value to be compared to and a colon. • The constant-expression for a case must be the same data type as the variable in the switch, and it must be a constant or a literal. • When the variable being switched on is equal to a case, the statements following that case will execute until a break statement is reached. • When a break statement is reached, the switch terminates, and the flow of control jumps to the next line following the switch statement. • Not every case needs to contain a break. If no break appears, the flow of control will fall through to subsequent cases until a break is reached. • A switch statement can have an optional default case, which must appear at the end of the switch. The default case can be used for performing a task when none of the cases is true. No break is needed in the default case.
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/* switch case statement in C language*/ // Program to create a simple calculator #include <stdio.h> int main() { char operation; double n1, n2; printf("Enter an operator (+, -, *, /): "); scanf("%c", &operation); printf("Enter two operands: "); scanf("%lf %lf",&n1, &n2); switch(operation) { case '+': printf("%.1lf + %.1lf = %.1lf",n1, n2, n1+n2); break; case '-': printf("%.1lf - %.1lf = %.1lf",n1, n2, n1-n2); break; case '*': printf("%.1lf * %.1lf = %.1lf",n1, n2, n1*n2); break; case '/': printf("%.1lf / %.1lf = %.1lf",n1, n2, n1/n2); break; // operator doesn't match any case constant +, -, *, / default: printf("Error! operator is not correct"); } return 0; }
getche() Function in C
Get the next keystroke from the console, and echo it. getche() function is a function in C programming language which waits for any character input from keyboard and it will also echo the input character on to the output screen. getche() function echoes the character to the screen whereas getch() does not do so. This is the only difference between both the functions. It can be remembered by the use of character 'e' at the end of getche() function.
Syntax for getche() Function in C
#include <conio.h> int getche(void);
Function returns the value of the keystroke (or character), or EOF if an error is detected. When the keystroke represents an extended function key (for example, a function key, a cursor-movement key or the ALT key with a letter or a digit), 0xff is returned and the next call to getche() returns a value for the extended function.
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/* read a single character from the keyboard and displays immediately on output screen without waiting for enter key by getche() function example */ #include <stdio.h> int main() { char flag; /* Our first simple C basic program */ printf("Hello World! "); printf("Do you want to continue Y or N"); flag = getche(); // It waits for keyboard input. if (flag == 'Y') { printf("You have entered Yes"); } else { printf("You have entered No"); } return 0; }
getch() Function in C
The getch() is a predefined non-standard function that is defined in conio.h header file. It is mostly used by the Dev C/C++, MS- DOS's compilers like Turbo C to hold the screen until the user passes a single value to exit from the console screen. It can also be used to read a single byte character or string from the keyboard and then print. It does not hold any parameters. It has no buffer area to store the input character in a program.
Syntax for getch() Function in C
#include <conio.h> int getch(void);
The getch() function does not accept any parameter from the user. It returns the ASCII value of the key pressed by the user as an input. We use a getch() function in a C/ C++ program to hold the output screen for some time until the user passes a key from the keyboard to exit the console screen. Using getch() function, we can hide the input character provided by the users in the ATM PIN, password, etc. • getch() method pauses the Output Console until a key is pressed. • It does not use any buffer to store the input character. • The entered character is immediately returned without waiting for the enter key. • The entered character does not show up on the console. • The getch() method can be used to accept hidden inputs like password, ATM pin numbers, etc.
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/* wait for any character input from keyboard by getch() function example. */ // C code to illustrate working of // getch() to accept hidden inputs #include <conio.h> #include <dos.h> // delay() #include <stdio.h> #include <string.h> void main() { // Taking the password of 8 characters char pwd[9]; int i; // To clear the screen clrscr(); printf("Enter Password: "); for (i = 0; i < 8; i++) { // Get the hidden input // using getch() method pwd[i] = getch(); // Print * to show that // a character is entered printf("*"); } pwd[i] = '\0'; printf("\n"); // Now the hidden input is stored in pwd[] // So any operation can be done on it // Here we are just printing printf("Entered password: "); for (i = 0; pwd[i] != '\0'; i++) printf("%c", pwd[i]); // Now the console will wait // for a key to be pressed getch(); }
setcolor() Function in C
setcolor() function is used to set the foreground color in graphics mode. After resetting the foreground color you will get the text or any other shape which you want to draw in that color. setcolor sets the current drawing color to color, which can range from 0 to getmaxcolor. The current drawing color is the value to which pixels are set when lines, and so on are drawn. The drawing colors shown below are available for the CGA and EGA, respectively.
Syntax for setcolor() Function in C
#include <graphics.h> void setcolor(int color);
Each color is assigned a number. The possible color values are from 0 - 15: • BLACK – 0 • BLUE – 1 • GREEN – 2 • CYAN – 3 • RED – 4 • MAGENTA – 5 • BROWN – 6 • LIGHTGRAY – 7 • DARKGRAY – 8 • LIGHTBLUE – 9 • LIGHTGREEN – 10 • LIGHTCYAN – 11 • LIGHTRED – 12 • LIGHTMAGENTA – 13 • YELLOW – 14 • WHITE – 15 setcolor() functions contains only one argument that is color. It may be the color name enumerated in graphics.h header file or number assigned with that color.
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/* set the current drawing color to color, which can range from 0 to getmaxcolor by setcolor() function example */ // C Implementation for setcolor() #include <graphics.h> #include <stdio.h> // driver code int main() { // gm is Graphics mode which is // a computer display mode that // generates image using pixels. // DETECT is a macro defined in // "graphics.h" header file int gd = DETECT, gm, color; // initgraph initializes the // graphics system by loading a // graphics driver from disk initgraph(&gd, &gm, ""); // Draws circle in white color // center at (100, 100) and radius // as 50 circle(100, 100, 50); // setcolor function setcolor(GREEN); // Draws circle in green color // center at (200, 200) and radius // as 50 circle(200, 200, 50); getch(); // closegraph function closes the // graphics mode and deallocates // all memory allocated by // graphics system . closegraph(); return 0; }
getmaxy() Function in C
The header file graphics.h contains getmaxy() function which returns the maximum Y coordinate for current graphics mode and driver. getmaxy returns the maximum (screen-relative) y value for the current graphics driver and mode. For example, on a CGA in 320*200 mode, getmaxy returns 199. getmaxy is invaluable for centering, determining the boundaries of a region onscreen, and so on.
Syntax for getmaxy() Function in C
#include <graphics.h> int getmaxy(void);
getmaxy() returns the maximum y screen coordinate. getmaxy() function is used to fetch the maximum Y coordinate for the current graphics mode or driver.
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/* get the maximum Y coordinate for current graphics mode and driver by getmaxy() function code example */ #include <graphics.h> #include <stdio.h> // driver code int main() { // gm is Graphics mode which is // a computer display mode that // generates image using pixels. // DETECT is a macro defined in // "graphics.h" header file int gd = DETECT, gm; char arr[100]; // initgraph initializes the // graphics system by loading a // graphics driver from disk initgraph(&gd, &gm, ""); // sprintf stands for "String print". // Instead of printing on console, it // store output on char buffer which // are specified in sprintf sprintf(arr, "Maximum Y coordinate for current " "graphics mode And driver = %d", getmaxy()); // outtext function displays text at // current position. outtext(arr); getch(); // closegraph function closes the // graphics mode and deallocates // all memory allocated by // graphics system . closegraph(); return 0; }
printf() Function in C
Writes the C string pointed by format to the standard output (stdout). If format includes format specifiers (subsequences beginning with %), the additional arguments following format are formatted and inserted in the resulting string replacing their respective specifiers. printf format string refers to a control parameter used by a class of functions in the input/output libraries of C programming language. The string is written in a simple template language: characters are usually copied literally into the function's output, but format specifiers, which start with a % character, indicate the location and method to translate a piece of data (such as a number) to characters. "printf" is the name of one of the main C output functions, and stands for "print formatted". printf format strings are complementary to scanf format strings, which provide formatted input (parsing). In both cases these provide simple functionality and fixed format compared to more sophisticated and flexible template engines or parsers, but are sufficient for many purposes.
Syntax for printf() function in C
#include <stdio.h> int printf ( const char * format, ... );
format
C string that contains the text to be written to stdout. It can optionally contain embedded format specifiers that are replaced by the values specified in subsequent additional arguments and formatted as requested. A format specifier follows this prototype: [see compatibility note below] %[flags][width][.precision][length]specifier Where the specifier character at the end is the most significant component, since it defines the type and the interpretation of its corresponding argument:
specifier
a conversion format specifier.
d or i
Signed decimal integer
u
Unsigned decimal integer
o
Unsigned octal
x
Unsigned hexadecimal integer
X
Unsigned hexadecimal integer (uppercase)
f
Decimal floating point, lowercase
F
Decimal floating point, uppercase
e
Scientific notation (mantissa/exponent), lowercase
E
Scientific notation (mantissa/exponent), uppercase
g
Use the shortest representation: %e or %f
G
Use the shortest representation: %E or %F
a
Hexadecimal floating point, lowercase
A
Hexadecimal floating point, uppercase
c
Character
s
String of characters
p
Pointer address
n
Nothing printed. The corresponding argument must be a pointer to a signed int. The number of characters written so far is stored in the pointed location.
%
A % followed by another % character will write a single % to the stream. The format specifier can also contain sub-specifiers: flags, width, .precision and modifiers (in that order), which are optional and follow these specifications:
flags
one or more flags that modifies the conversion behavior (optional)
-
Left-justify within the given field width; Right justification is the default (see width sub-specifier).
+
Forces to preceed the result with a plus or minus sign (+ or -) even for positive numbers. By default, only negative numbers are preceded with a - sign.
(space)
If no sign is going to be written, a blank space is inserted before the value.
#
Used with o, x or X specifiers the value is preceeded with 0, 0x or 0X respectively for values different than zero. Used with a, A, e, E, f, F, g or G it forces the written output to contain a decimal point even if no more digits follow. By default, if no digits follow, no decimal point is written.
0
Left-pads the number with zeroes (0) instead of spaces when padding is specified (see width sub-specifier).
width
an optional * or integer value used to specify minimum width field.
(number)
Minimum number of characters to be printed. If the value to be printed is shorter than this number, the result is padded with blank spaces. The value is not truncated even if the result is larger.
*
The width is not specified in the format string, but as an additional integer value argument preceding the argument that has to be formatted.
.precision
an optional field consisting of a . followed by * or integer or nothing to specify the precision.
.number
For integer specifiers (d, i, o, u, x, X): precision specifies the minimum number of digits to be written. If the value to be written is shorter than this number, the result is padded with leading zeros. The value is not truncated even if the result is longer. A precision of 0 means that no character is written for the value 0. For a, A, e, E, f and F specifiers: this is the number of digits to be printed after the decimal point (by default, this is 6). For g and G specifiers: This is the maximum number of significant digits to be printed. For s: this is the maximum number of characters to be printed. By default all characters are printed until the ending null character is encountered. If the period is specified without an explicit value for precision, 0 is assumed.
.*
The precision is not specified in the format string, but as an additional integer value argument preceding the argument that has to be formatted.
length
an optional length modifier that specifies the size of the argument.
... (additional arguments)
Depending on the format string, the function may expect a sequence of additional arguments, each containing a value to be used to replace a format specifier in the format string (or a pointer to a storage location, for n). There should be at least as many of these arguments as the number of values specified in the format specifiers. Additional arguments are ignored by the function. If a writing error occurs, the error indicator (ferror) is set and a negative number is returned. If a multibyte character encoding error occurs while writing wide characters, errno is set to EILSEQ and a negative number is returned.
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/* print formatted data to stdout by printf() function example */ #include <stdio.h> int main() { char ch; char str[100]; int a; float b; printf("Enter any character \n"); scanf("%c", &ch); printf("Entered character is %c \n", ch); printf("Enter any string ( upto 100 character ) \n"); scanf("%s", &str); printf("Entered string is %s \n", str); printf("Enter integer and then a float: "); // Taking multiple inputs scanf("%d%f", &a, &b); printf("You entered %d and %f", a, b); return 0; }
delay() Function in C
Delay function is used to suspend execution of a program for a particular time. delay() function requires a parameter which should be a number, defining the milliseconds for the delay. To use delay function in your program you should include the "dos.h" header file which is not a part of standard C library. Here unsigned int is the number of milliseconds (remember 1 second = 1000 milliseconds).
Syntax for delay() Function in C
#include<stdio.h> void delay(unsigned int);
sleep() function requires a parameter which should be a number, defining the seconds to sleep. These functions are pretty useful when you want to show the user multiple outputs, for a given period of time. The nice thing about this is that we can also make alarm and reminder for the user in our program. Hence, these two functions are pretty handy, if you are planning to make a real-world application.
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/* suspend execution of a program for a particular time by delay() function example */ #include <stdio.h> //to use 'delay()' #include <dos.h> int main() { // message for user printf("After printing this message the program will get end in next 5 seconds \n"); // delay the process for 5 seconds as it takes integer value in milliseconds. delay(5000); // message for user. printf("After printing this message the program will get delay for next 15 seconds\n"); // to terminate the process for next 15 seconds. sleep(15); // message for user printf("After printing this message the program will get end in next 2 seconds \n"); // delay the process for 2 seconds as it takes integer value in milliseconds. delay(2000); return 0; }
closegraph() Function in C
The header file graphics.h contains closegraph() function which closes the graphics mode, deallocates all memory allocated by graphics system and restores the screen to the mode it was in before you called initgraph. closegraph() function is used to re-enter in the text mode and exit from the graphics mode. If you want to use both text mode and graphics mode in the program then you have to use both initgraph() and closegraph() function in the program.
Syntax for closegraph() Function in C
#include <graphics.h> void closegraph();
This function does not return any value.
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/* deallocate all memory allocated by the graphics system by closegraph() function example */ // C Implementation for closegraph() #include <graphics.h> // driver code int main() { // gm is Graphics mode which is // a computer display mode that // generates image using pixels. // DETECT is a macro defined in // "graphics.h" header file int gd = DETECT, gm; // initgraph initializes the // graphics system by loading a // graphics driver from disk initgraph(&gd, &gm, ""); // outtext function displays // text at current position. outtext("Press any key to close" " the graphics mode !!"); getch(); // closegraph function closes the // graphics mode and deallocates // all memory allocated by // graphics system . closegraph(); return 0; }


C program print all prime numbers between 1 to n. Input upper & lower limit to print prime. Find Prime numbers between 1 to n. Assume that the current number is Prime and check if
Enter the number of queens(say n) and watch how computer places them in (n x n) matrix such that none can meet another moving along horizontally, vertically or digonally.
C Program determines the given matrix is a sparse matrix. Sparse matrix is a matrix with the majority of its elements equal to zero. Accept matrix and checks whether the given