string : c

strrchr

function

const char * strrchr ( const char * str, int character ); char * strrchr ( char * str, int character );

Locate last occurrence of character in string

Returns a pointer to the last occurrence of character in the C string str.

The terminating null-character is considered part of the C string. Therefore, it can also be located to retrieve a pointer to the end of a string.

即使n 大于字符串其中之一的长度也是可以的。
大于2个也是也可以的。:)

#include <string.h>

int
strncmp(s1, s2, n)
    register const char *s1, *s2;
    register size_t n;
{

    if (n == 0)
        return (0);
    do {
        if (*s1 != *s2++)
            return (*(const unsigned char *)s1 -
                *(const unsigned char *)(s2 - 1));
        if (*s1++ == 0)
            break;
    } while (--n != 0);
    return (0);
}