strncpy和strlen的可能的实现

#include <stdio.h>

#include <stdlib.h>
//为避免与标准库中的函数发生混淆，我将它们命名为stringNCopy和stringLength

char *stringNCopy(char *dest, const char *src, size_t count)

{

    for (size_t i = 0; i < count; ++i)

    {

        dest[i] = src[i];

        if (!src[i])

        {

            break;

        }

    }

    return dest;

}

size_t stringLength(const char *str)

{

    size_t count = 0;

    while (*str++)

    {

        ++count;

    }

    return count;

}

int main()

{

    char *dest = malloc(sizeof(char) * 100);

    const char *src = "hello world
世界你好";

    stringNCopy(dest, src, stringLength(src) + 1);

    printf("%s
", dest);

    free(dest);

    char arr[50];

    char *ret = stringNCopy(arr, "programming 程序设计", 10000);

    printf("%s
%s
", arr, ret);

    ret = stringNCopy(arr, "Programmer", 1);

    printf("%s
%s
", arr, ret);

    char test[2];

    const char *str = "测试Test";

    ret = stringNCopy(test, str, 100); //非法的操作，可通过编译，但是运行之后可能会报错（vc++下编译并运行之后会报错，Windows下gcc编译后运行无报错）

    printf("%s
%s
", test, ret);

    printf("%u
%u
%u
", stringLength(""), stringLength(""), stringLength("字符串 String"));

    return 0;

}