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C Programming Code Examples

C > Small Programs Code Examples

Print several types of alphabets

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/* Print several types of alphabets */ #include <stdio.h> #include <ctype.h> #include <getopt.h> #define PACKAGE "alphabet" #define VERSION "0.0.5" /* // `0' westeren, `1' phonetic, `2' greek `3' hebrew // `4' phoenician `5' arab */ static int type = 0; /* all output upper case */ static int upper = 0; /* recursive, output until killed */ static int recur = 0; /* phonetic alphabet */ const char *palpha[]= { "alpha", "bravo", "charlie", "delta", "echo", "foxtrot", "golf", "hotel", "india", "juliet", "kilo", "lima", "mike", "november", "oscar", "papa", "quebec", "romeo", "sierra", "tango", "uniform", "victor", "whisky", "x-ray", "yankee", "zulu" }; /* lower case greek alphabet */ const char *galpha[]= { "alpha", "beta", "gamma", "delta", "epsilon", "zeta", "eta", "theta", "iota", "kappa", "lambda", "mu", "nu", "xi", "omicron", "pi", "rho", "sigma", "tau", "upsilon", "phi", "chi", "psi", "omega" }; /* lower case hebrew alphabet */ const char *halpha[]= { "tet", "chet", "zayin", "vav", "he", "dalet", "gimel", "bet", "alef", "samech", "nun", "nun", "mem", "mem", "lamed", "khaf", "kaf", "yod", "tav", "shin", "resh", "qof", "tzade", "tzade", "fe", "pe", "ayin" }; /* lower case phoenician alphabet */ const char *nalpha[]= { "aleph", "beth", "gimel", "daleth", "he", "waw", "heth", "yodh", "kaph", "lamedh", "mem", "nun", "ayin", "pe", "qoph", "resh", "sin", "taw", "waw", "samekh", "zayin" }; /* lower case arab alphabet */ const char *aalpha[]= { "xaa", "haa", "jiim", "th!aa", "taa", "baa", "alif", "saad", "shiin", "siin", "zaay", "raa", "thaal", "daal", "qaaf", "faa", "ghayn", "ayn", "th:aa", "taa", "daad", "yaa", "waaw", "haa", "nuun", "miim", "laam", "kaaf" }; /* status epilepticus, and die with `exval' */ void print_help(int exval); /* print the specified alphabet */ void print_alphabet(void); int main(int argc, char *argv[]) { int opt = 0; /* option parser */ while((opt = getopt(argc, argv, "hvpgwiaru")) != -1) { switch(opt) { case 'h': /* print help and exit */ print_help(0); case 'v': /* print version and exit */ exit(0); case 'p': /* print the phonetic alphabet */ type = 1; break; case 'g': /* print the lower case greek alphabet */ type = 2; break; case 'w': /* print the lower case hebrew alphabet */ type = 3; break; case 'i': /* print the lower case phoenician alphabet */ type = 4; break; case 'a': /* print the lower case arab alphabet */ type = 5; break; case 'r': /* print the alphabet repeatedly until killed */ recur = 1; break; case 'u': /* print all output upper case */ upper = 1; break; case '?': /* unkown option */ fprintf(stderr, "%s: Error - no such option `%c'\n\n", PACKAGE, optopt); print_help(1); break; } /* switch */ } /* while */ /* prints the selected alphabet */ print_alphabet(); return 0; } /* prints the selected alphabet */ void print_alphabet(void) { const char *ptr = NULL; int i = 0; /* western alphabet */ if(type == 0) { if(upper == 0) for(i = 97; i <= 122; i++) printf("%c\n", i); else for(i = 65; i <= 90; i++) printf("%c\n", i); /* phonetic alphabet */ } else if(type == 1) { if(upper == 0) { for(i = 0; i < 26; i++) printf("%s\n", palpha[i]); } else { for(i = 0; i < 26; i++) { ptr = palpha[i]; while(*ptr) printf("%c", toupper(*ptr++)); printf("\n"); } /* for */ } /* else */ /* greek alphabet */ } else if(type == 2) { if(upper == 0) { for(i = 0; i < 24; i++) printf("%s\n", galpha[i]); } else { for(i = 0; i < 24; i++) { ptr = galpha[i]; while(*ptr) printf("%c", toupper(*ptr++)); printf("\n"); } /* for */ } /* else */ } else if(type == 3) { if(upper == 0) { for(i = 0; i < 27; i++) printf("%s\n", halpha[i]); } else { for(i = 0; i < 27; i++) { ptr = halpha[i]; while(*ptr) printf("%c", toupper(*ptr++)); printf("\n"); } /* for */ } /* else */ } else if(type == 4) { if(upper == 0) { for(i = 0; i < 21; i++) printf("%s\n", nalpha[i]); } else { for(i = 0; i < 21; i++) { ptr = nalpha[i]; while(*ptr) printf("%c", toupper(*ptr++)); printf("\n"); } /* for */ } /* else */ } else if(type == 5) { if(upper == 0) { for(i = 0; i < 28; i++) printf("%s\n", aalpha[i]); } else { for(i = 0; i < 28; i++) { ptr = aalpha[i]; while(*ptr) printf("%c", toupper(*ptr++)); printf("\n"); } /* for */ } /* else */ } /* else if */ if(recur == 1) print_alphabet(); else return; } /* status epilepticus, and die with `exval' */ void print_help(int exval) { printf("%s,%s prints different alphabets\n", PACKAGE, VERSION); printf("Usage: %s [-h] [-v] [-p] [-g] [-w] [-i] [-a] [-r] [-u]\n\n", PACKAGE); printf(" Startup:\n"); printf(" -h print this help and exit\n"); printf(" -v print version and exit\n\n"); printf(" Alphabet:\n"); printf(" -p print the phonetic alphabet\n"); printf(" -g print the greek alphabet\n"); printf(" -w print the hebrew alphabet\n"); printf(" -i print the phoenician alphabet\n"); printf(" -a print the arab alphabet\n\n"); printf(" Output:\n"); printf(" -r print the alphabet repeatedly until killed\n"); printf(" -u print all output in upper case\n\n"); printf(" Per default the Westeren alphabet is printed\n"); exit(exval); }
getopt() Function in C
The getopt() function is a builtin function in C and is used to parse command line arguments. The getopt() function is a command-line parser that shall follow Utility Syntax Guidelines 3, 4, 5, 6, 7, 9, and 10 in the Base Definitions volume of IEEE Std 1003.1-2001, Section 12.2, Utility Syntax Guidelines. The parameters argc and argv are the argument count and argument array as passed to main() (see exec() ). The argument optstring is a string of recognized option characters; if a character is followed by a colon, the option takes an argument. All option characters allowed by Utility Syntax Guideline 3 are allowed in optstring. The implementation may accept other characters as an extension.
Syntax for getopt() Function in C
#include <unistd.h> int getopt(int argc, char * const argv[], const char *optstring); extern char *optarg; extern int optind, opterr, optopt;
argc
The argument count that was passed to main().
argv
The argument array that was passed to main().
optstring
A string of recognized option letters; if a letter is followed by a colon, the option takes an argument. Valid option characters for optstring consist of a single alphanumeric character (i.e. a letter or digit). The variable optind is the index of the next element of the argv[] vector to be processed. It shall be initialized to 1 by the system, and getopt() shall update it when it finishes with each element of argv[]. When an element of argv[] contains multiple option characters, it is unspecified how getopt() determines which options have already been processed. The getopt() function shall return the next option character (if one is found) from argv that matches a character in optstring, if there is one that matches. If the option takes an argument, getopt() shall set the variable optarg to point to the option-argument as follows: 1- If the option was the last character in the string pointed to by an element of argv, then optarg shall contain the next element of argv, and optind shall be incremented by 2. If the resulting value of optind is greater than argc, this indicates a missing option-argument, and getopt() shall return an error indication. 2- Otherwise, optarg shall point to the string following the option character in that element of argv, and optind shall be incremented by 1. If, when getopt() is called:
argv[optind] is a null pointer *argv[optind] is not the character - argv[optind] points to the string "-"
getopt() shall return -1 without changing optind. If:
argv[optind] points to the string "--"
getopt() shall return -1 after incrementing optind. If getopt() encounters an option character that is not contained in optstring, it shall return the question-mark ( '?' ) character. If it detects a missing option-argument, it shall return the colon character ( ':' ) if the first character of optstring was a colon, or a question-mark character ( '?' ) otherwise. In either case, getopt() shall set the variable optopt to the option character that caused the error. If the application has not set the variable opterr to 0 and the first character of optstring is not a colon, getopt() shall also print a diagnostic message to stderr in the format specified for the getopts utility. The getopt() function need not be reentrant. A function that is not required to be reentrant is not required to be thread-safe. The getopt() function shall return the next option character specified on the command line. A colon ( ':' ) shall be returned if getopt() detects a missing argument and the first character of optstring was a colon ( ':' ). A question mark ( '?' ) shall be returned if getopt() encounters an option character not in optstring or detects a missing argument and the first character of optstring was not a colon ( ':' ). Otherwise, getopt() shall return -1 when all command line options are parsed.
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/* parse command line arguments by getopt() function code example */ // Program to illustrate the getopt() // function in C #include <stdio.h> #include <unistd.h> int main(int argc, char *argv[]) { int opt; // put ':' in the starting of the // string so that program can //distinguish between '?' and ':' while((opt = getopt(argc, argv, ":if:lrx")) != -1) { switch(opt) { case 'i': case 'l': case 'r': printf("option: %c\n", opt); break; case 'f': printf("filename: %s\n", optarg); break; case ':': printf("option needs a value\n"); break; case '?': printf("unknown option: %c\n", optopt); break; } } // optind is for the extra arguments // which are not parsed for(; optind < argc; optind++){ printf("extra arguments: %s\n", argv[optind]); } return 0; }
While Loop Statement in C
While loop is also known as a pre-tested loop. In general, a while loop allows a part of the code to be executed multiple times depending upon a given boolean condition. It can be viewed as a repeating if statement. The while loop is mostly used in the case where the number of iterations is not known in advance. The while loop evaluates the test expression inside the parentheses (). If test expression is true, statements inside the body of while loop are executed. Then, test expression is evaluated again. The process goes on until test expression is evaluated to false. If test expression is false, the loop terminates.
Syntax of While Loop Statement in C
while (testExpression) { // the body of the loop }
• The while loop evaluates the testExpression inside the parentheses (). • If testExpression is true, statements inside the body of while loop are executed. Then, testExpression is evaluated again. • The process goes on until testExpression is evaluated to false. • If testExpression is false, the loop terminates (ends).
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/* while loop statement in C language */ #include<stdio.h> int main() { int n, num, sum = 0, remainder; printf("Enter a number: "); scanf("%d", &n); num = n; // keep looping while n > 0 while( n > 0 ) { remainder = n % 10; // get the last digit of n sum += remainder; // add the remainder to the sum n /= 10; // remove the last digit from n } printf("Sum of digits of %d is %d", num, sum); // signal to operating system everything works fine return 0; }
exit() Function in C
The exit() function is used to terminate a process or function calling immediately in the program. It means any open file or function belonging to the process is closed immediately as the exit() function occurred in the program. The exit() function is the standard library function of the C, which is defined in the stdlib.h header file. So, we can say it is the function that forcefully terminates the current program and transfers the control to the operating system to exit the program. The exit(0) function determines the program terminates without any error message, and then the exit(1) function determines the program forcefully terminates the execution process.
Syntax for exit() Function in C
#include <stdlib.h> void exit(int status)
status
Status code. If this is 0 or EXIT_SUCCESS, it indicates success. If it is EXIT_FAILURE, it indicates failure. The exit function does not return anything. • We must include the stdlib.h header file while using the exit () function. • It is used to terminate the normal execution of the program while encountered the exit () function. • The exit () function calls the registered atexit() function in the reverse order of their registration. • We can use the exit() function to flush or clean all open stream data like read or write with unwritten buffered data. • It closed all opened files linked with a parent or another function or file and can remove all files created by the tmpfile function. • The program's behaviour is undefined if the user calls the exit function more than one time or calls the exit and quick_exit function. • The exit function is categorized into two parts: exit(0) and exit(1).
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/* call all functions registered with atexit and terminates the program by exit() function example */ #include <stdio.h> #include <stdlib.h> int main () { // declaration of the variables int i, num; printf ( " Enter the last number: "); scanf ( " %d", &num); for ( i = 1; i<num; i++) { // use if statement to check the condition if ( i == 6 ) /* use exit () statement with passing 0 argument to show termination of the program without any error message. */ exit(0); else printf (" \n Number is %d", i); } return 0; }
toupper() Function in C
Convert lowercase letter to uppercase. Converts c to its uppercase equivalent if c is a lowercase letter and has an uppercase equivalent. If no such conversion is possible, the value returned is c unchanged. Notice that what is considered a letter may depend on the locale being used; In the default "C" locale, a lowercase letter is any of: a b c d e f g h i j k l m n o p q r s t u v w x y z, which translate respectively to: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z. In other locales, if a lowercase character has more than one correspondent uppercase character, this function always returns the same character for the same value of c. In C++, a locale-specific template version of this function (toupper) exists in header <locale>.
Syntax for toupper() Function in C
#include <ctype.h> int toupper ( int c );
c
Character to be converted, casted to an int, or EOF Function returns the uppercase equivalent to c, if such value exists, or c (unchanged) otherwise. The value is returned as an int value that can be implicitly casted to char. If the character passed is a lowercase alphabet then the toupper() function converts a lowercase alphabet to an uppercase alphabet. It is defined in the ctype.h header file.
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/* convert lowercase letter to uppercase by toupper() function example */ //Example for toupper in C Programming #include <stdio.h> #include <ctype.h> int main() { char ch; printf("Please Enter Any Valid Character: \n"); scanf("%c", &ch); if(isalpha(ch)) { printf("\n We Converted Your character to Upper Case = %c", toupper(ch)); } else { printf("\n Please Enter a Valid character"); } }
Nested Loop Statement in C
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. A loop inside another loop is called a nested loop. The depth of nested loop depends on the complexity of a problem. We can have any number of nested loops as required. Consider a nested loop where the outer loop runs n times and consists of another loop inside it. The inner loop runs m times. Then, the total number of times the inner loop runs during the program execution is n*m.
Syntax for Nested Loop Statement in C
Outer_loop { Inner_loop { // inner loop statements. } // outer loop statements. }
Outer_loop and Inner_loop are the valid loops that can be a 'for' loop, 'while' loop or 'do-while' loop.
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/* nested loop statement in C language */ // C Program to print all prime factors // of a number using nested loop #include <math.h> #include <stdio.h> // A function to print all prime factors of a given number n void primeFactors(int n) { // Print the number of 2s that divide n while (n % 2 == 0) { printf("%d ", 2); n = n / 2; } // n must be odd at this point. So we can skip // one element (Note i = i +2) for (int i = 3; i <= sqrt(n); i = i + 2) { // While i divides n, print i and divide n while (n % i == 0) { printf("%d ", i); n = n / i; } } // This condition is to handle the case when n // is a prime number greater than 2 if (n > 2) printf("%d ", n); } /* Driver program to test above function */ int main() { int n = 315; primeFactors(n); 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; }
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; }
Break Statement in C
The break is a keyword in C which is used to bring the program control out of the loop. The break statement is used inside loops or switch statement. The break statement breaks the loop one by one, i.e., in the case of nested loops, it breaks the inner loop first and then proceeds to outer loops.
Syntax for Break Statement in C
//loop statement... break;
When a break statement is encountered inside a loop, the loop is immediately terminated and the program control resumes at the next statement following the loop. It can be used to terminate a case in the switch statement (covered in the next chapter). If you are using nested loops, the break statement will stop the execution of the innermost loop and start executing the next line of code after the block.
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/* bring the program control out of the loop by break keyword */ // Program to calculate the sum of numbers (10 numbers max) // If the user enters a negative number, the loop terminates #include <stdio.h> int main() { int i; double number, sum = 0.0; for (i = 1; i <= 10; ++i) { printf("Enter n%d: ", i); scanf("%lf", &number); // if the user enters a negative number, break the loop if (number < 0.0) { break; } sum += number; // sum = sum + number; } printf("Sum = %.2lf", sum); 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; }
fprintf() Function in C
Write formatted data to stream. Writes the C string pointed by format to the stream. 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. After the format parameter, the function expects at least as many additional arguments as specified by format.
Syntax for fprintf() Function in C
#include <stdio.h> int fprintf ( FILE * stream, const char * format, ... );
stream
Pointer to a FILE object that identifies an output stream.
format
C string that contains the text to be written to the stream. 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: %[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.
h
The argument is interpreted as a short int or unsigned short int (only applies to integer specifiers: i, d, o, u, x and X).
l
The argument is interpreted as a long int or unsigned long int for integer specifiers (i, d, o, u, x and X), and as a wide character or wide character string for specifiers c and s.
L
The argument is interpreted as a long double (only applies to floating point specifiers - e, E, f, g and G).
... (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. On success, the total number of characters written is returned. 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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/* write the C string pointed by format to the stream by fprintf() function example */ #include <stdio.h> void main() { FILE *fptr; int id; char name[30]; float salary; fptr = fopen("emp.txt", "w+");/* open for writing */ if (fptr == NULL) { printf("File does not exists \n"); return; } printf("Enter the id\n"); scanf("%d", &id); fprintf(fptr, "Id= %d\n", id); printf("Enter the name \n"); scanf("%s", name); fprintf(fptr, "Name= %s\n", name); printf("Enter the salary\n"); scanf("%f", &salary); fprintf(fptr, "Salary= %.2f\n", salary); fclose(fptr); }
#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; }
If Else If Ladder in C/C++
The if...else statement executes two different codes depending upon whether the test expression is true or false. Sometimes, a choice has to be made from more than 2 possibilities. The if...else ladder allows you to check between multiple test expressions and execute different statements. In C/C++ if-else-if ladder helps user decide from among multiple options. The C/C++ if statements are executed from the top down. As soon as one of the conditions controlling the if is true, the statement associated with that if is executed, and the rest of the C else-if ladder is bypassed. If none of the conditions is true, then the final else statement will be executed.
Syntax of if...else Ladder in C
if (Condition1) { Statement1; } else if(Condition2) { Statement2; } . . . else if(ConditionN) { StatementN; } else { Default_Statement; }
In the above syntax of if-else-if, if the Condition1 is TRUE then the Statement1 will be executed and control goes to next statement in the program following if-else-if ladder. If Condition1 is FALSE then Condition2 will be checked, if Condition2 is TRUE then Statement2 will be executed and control goes to next statement in the program following if-else-if ladder. Similarly, if Condition2 is FALSE then next condition will be checked and the process continues. If all the conditions in the if-else-if ladder are evaluated to FALSE, then Default_Statement will be executed.
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/* write a C program which demonstrate use of if-else-if ladder statement */ #include<stdio.h> #include<conio.h> void main() { int a; printf("Enter a Number: "); scanf("%d",&a); if(a > 0) { printf("Given Number is Positive"); } else if(a == 0) { printf("Given Number is Zero"); } else if(a < 0) { printf("Given Number is Negative"); } getch(); }
For Loop Statement in C
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.
Syntax of For Loop Statement in C
for (initialization; condition test; increment or decrement) { //Statements to be executed repeatedly }
Step 1
First initialization happens and the counter variable gets initialized.
Step 2
In the second step the condition is checked, where the counter variable is tested for the given condition, if the condition returns true then the C statements inside the body of for loop gets executed, if the condition returns false then the for loop gets terminated and the control comes out of the loop.
Step 3
After successful execution of statements inside the body of loop, the counter variable is incremented or decremented, depending on the operation (++ or --).
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/* for loop statement in C language */ // Program to calculate the sum of first n natural numbers // Positive integers 1,2,3...n are known as natural numbers #include <stdio.h> int main() { int num, count, sum = 0; printf("Enter a positive integer: "); scanf("%d", &num); // for loop terminates when num is less than count for(count = 1; count <= num; ++count) { sum += count; } printf("Sum = %d", sum); 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; }


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