strncpy函数模拟实现

strncpy函数在cplusplus网站中的定义

模拟实现源码

//模拟实现
#include <stdio.h>
#include <string.h>
#include <assert.h>char* my_strncpy(char* destination, const char* source, size_t num)
{assert(destination && source);//对指针进行断言，确保不是NULL指针char* ret = destination;//保存目的地址while (num--){*destination = *source;destination++;source++;}return ret;
}int main()
{char arr1[] = "abcdef";char arr2[20] = "xxxxxxxxxxxxxxx";char arr3[20] = { 0 };char* ret1 = my_strncpy(arr2, arr1, 4);char* ret2 = my_strncpy(arr3, arr1, 4);printf("arr1:%s\n", arr1);printf("arr2:%s\n", arr2);printf("ret1:%s\n", ret1);printf("arr3:%s\n", arr3);printf("ret2:%s\n", ret2);return 0;
}

执行结果