In C language, header files contain the set of predefined standard library functions. The “#include” preprocessing directive is used to include the header files with “.h” extension in the program.
1 stdio.h
Input/Output functions
2 conio.h
Console Input/Output functions
3 stdlib.h
General utility functions
4 math.h
Mathematics functions
5 string.h
String functions
6 ctype.h
Character handling functions
7 time.h
Date and time functions
8 float.h
Limits of float types
9 limits.h
Size of basic types
10 wctype.h
Example
#include <stdio.h>
#include<stdlib.h>
#include<string.h>
#include<math.h>
int main() {
char s1[20] = "53875";
char s2[10] = "Hello";
char s3[10] = "World";
int res;
res = pow(8, 4);
printf("Using math.h, The value is : %d\n", res);
long int a = atol(s1);
printf("Using stdlib.h, the string to long int : %d\n", a);
strcpy(s2, s3);
printf("Using string.h, the strings s2 and s3 : %s\t%s\n", s2, s3 );
return 0;
}
Output
Using math.h, The value is : 4096
Using stdlib.h, the string to long int : 53875
Using string.h, the strings s2 and s3 : World World
