C Primer Plus, Fourth Edition

String Functions

The C library supplies several string-handling functions; ANSI C uses the string.h header file to provide the prototypes. We'll look at some of the most useful and common ones: strlen(), strcat(), strncat(), strcmp(), strncmp(), strcpy(), and strncpy(). We'll also examine sprintf(), supported by the stdio.h header file. For a complete list of the string.h family of functions, see Reference Section V, “The ANSI C Library.”

The strlen() Function

The strlen() function, as you already know, finds the length of a string. It's used in the next example, a function that shortens lengthy strings:

/* fit.c -- procrustean function */
void fit(char * string, unsigned int size)
{
    if (strlen(string) > size)
        *(string + size) = '\0';
}

This ...