c语言中strncpy函数

1、函数原型。

#include <stdio.h>


char *strncpy(char *s1, const char *s2, size_t n)
{
    char *tmp = s1;
    
    while(n)
    {
        if(!(*s1++ = *s2++))
            break;
        n--;
    }
    
    while(n--)
        *s1++ = '';
    return tmp;
}

int main(void)
{
    char str[128];
    char test[128] = "abcdefg";
    
    printf("result: %s
", strncpy(str, test, 4));
    return 0;
}

2、

#include <stdio.h>
#include <string.h>

int main(void)
{
    char str[128];
    char tmp[128] = "abcdefg";
    
    printf("result: %s
", strncpy(str, tmp, 5));
    return 0;
}