In C programming there are too many standard library functions. Standard library functions are predefined functions in C programming, which get installed in our computer while stalling C programming software i.e. C IDE, these functions are used in writing programs for example to print output screen we use printf() function, which is declared in stdio.h header file.
Like printf() there are too many standard library functions and they are defined in various header files. Some of standard library functions are below.
printf()
scanf()
getchar()
putchar()
fopen()
fclose()
All above fuctions are standard libray functions and they are defined in stdio.h header file.
strcat()
strcpy()
strcmp()
All 3 above functions are also standard library functions and they are defined in string.h header file.
To add header file in the program we use #include<header_file.h> at top of the program. See below program.
#include<stdio.h>
void main()
{
printf("Hello this is Ravi");
}