C Programming Code Examples
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Display text using Bios routines
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/* Display text using Bios routines */
#include<stdio.h>
#include<dos.h>
#include<conio.h>
void main()
{
union REGS in,out,ins,oust;
int i,j,row=0,col=0,colaux;
char sentence[80];
clrscr();
gotoxy(1,1);
printf("ENTER A STATEMENT : ");
gets(sentence);
clrscr();
in.h.ah=0x00;in.h.al=0x12;int86(0x10,&in,&out);
in.h.ah=0x0F;
int86(0x10,&in,&out);
printf("
Video Mode = %u",out.h.al);
printf("
Number Of Chararowers Column On Screen = %u",out.h.ah);
printf("
Page Number = %u
",out.h.bh);
gotoxy(1,1);
printf("%s",sentence);
in.h.ah=0x0D;
in.h.bh=0;
ins.h.ah=0x0C;ins.h.bh=0;
for(i=0;i<15;i++)
{
row=0;col=0;
for(j=0;j<640;j++)
{
in.x.dx=i;
in.x.cx=j;
ins.h.al=i+1;
colaux=col*3; //adjusting text width
if(colaux%640==0)
{
row+=55;
col=0;
}
ins.x.cx=colaux;
ins.x.dx=i*3+150+row;
//adjusting text height;'150':-point where text starts
int86(0x10,&in,&out);
if(out.h.al!=0) int86(0x10,&ins,&oust);
//printf("%u,",out.h.al);
col++;
}
}
getch();
in.h.ah=0x00;in.h.al=3;int86(0x10,&in,&out);
}
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,
Get string from stdin. Reads characters from the standard input (stdin) and stores them as a C string into str until a newline character or the end-of-file is reached. The newline character, if found, is not copied into str. A terminating null character is automatically appended after the characters copied to str. Notice that gets is quite different from fgets: not only gets uses stdin as source, but it does not include the ending newline character in the resulting string and does not allow to specify a maximum size for str (which can lead to buffer overflows).
Function clrscr() clears the screen and moves the cursor to the upper left-hand corner of the screen. If you are using the GCC compiler, use system function to execute the clear/cls command. clrscr() function is also a non-standard function defined in "conio.h" header. This function is used to clear the console screen. It is often used at the beginning of the program (mostly after variable declaration but not necessarily) so that the console is clear for our output.
A union is a special data type available in C that allows to store different data types in the same memory location. You can define a union with many members, but only one member can contain a value at any given time. Unions provide an efficient way of using the same memory location for multiple-purpose. To define a union, you must use the union statement in the same way as you did while defining a structure. The union statement defines a new data type with more than one member for your program. The format of the union statement is as follows:
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.
Assignment operators are used to assign the value, variable and function to another variable. Assignment operators in C are some of the C Programming Operator, which are useful to assign the values to the declared variables. Let's discuss the various types of the assignment operators such as =, +=, -=, /=, *= and %=. The following table lists the assignment operators supported by the C language: Simple assignment operator. Assigns values from right side operands to left side operand. Add AND assignment operator. It adds the right operand to the left operand and assign the result to the left operand.
C supports nesting of loops in C. Nesting of loops is the feature in C that allows the looping of statements inside another loop. Any number of loops can be defined inside another loop, i.e., there is no restriction for defining any number of loops. The nesting level can be defined at n times. You can define any type of loop inside another loop; for example, you can define 'while' loop inside a 'for' loop.
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.
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.
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.
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.
#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:
The for loop is used in the case where we need to execute some part of the code until the given condition is satisfied. The for loop is also called as a per-tested loop. It is better to use for loop if the number of iteration is known in advance. The for-loop statement is a very specialized while loop, which increases the readability of a program. It is frequently used to traverse the data structures like the array and linked list.
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