The fputs() function is used to write the contents of the string pointed to by str to the specified stream. Here the null terminator is not written
#include<stdio.h> int fputs(const char *str, FILE *stream);
The fputs() function returns non-negative on success, otherwise it will returns EOF on failures.
Following c code writes string this is a test to the stream pointed to by fp
fputs("this is a test", fp);