#include <string.h>
void *memset (void * s , int c ,
size_t n );
The memset function copies the value of c (converted to an unsigned char) into each of the first n characters of the object pointed to by s.
The memset function returns the value of s.
None.
#include <string.h>
char *strerror (int
errnum );
The strerror function maps the error number in errnum to an error message string.
The implementation shall behave as if no library function calls the strerror function.
The strerror function returns a pointer to the string, the contents of which are implementation defined.
None.
#include <string.h>
size_t
strlen (char * s
);
The strlen function computes the length of the string pointed to by s.
The strlen function returns the number of characters that precede the terminating null character.