C 标准库 strlen 函数的实现

/*
 * strlen 返回 字符串 的长度
 */

#include <cstdio>

size_t strlen ( const char * str ) {
    char *p = (char *)str;
    while (*p++ != '\0')
        ;

    return p-1-str;
}

int main ()
{
    char szInput[256];
    printf ("Enter a sentence: ");
    gets (szInput);
    printf ("The sentence entered is %u characters long.\n",(unsigned)strlen(szInput));
    return 0;
}