char* strcpy( char* dest, const char* src ), int binary_search(int *arr, int key, int n), 可能的实现

#include <stdio.h>

char* stringCopy( char* dest, const char* src )

{

    size_t i = 0;

    while (dest[i] = src[i++]);

    return dest;

}

int binary_search(int *arr, int key, int n)

{

    int i = n / 2;

    if (arr[i] < key)

    {

        for ( ++i; i < n; ++i)

        {

            if (arr[i] == key) return i;

        }

    }

    else

    {

        for (; i > -1; --i)

        {

            if (arr[i] == key) return i;

        }

    }

    return -1;

}

int main()

{

    char strBuf[100];

    char *ret = stringCopy(strBuf, "This is a test!\n这是一个测试！");

    printf("%s\n", strBuf);

    printf("%s\n", ret);

    int ints[] = { 1, 3, 5, 7, 9 };

    printf("%d\n", binary_search(ints, 5, sizeof ints / sizeof(int)));

    printf("%d\n", binary_search(ints, -1, sizeof ints/ sizeof(int)));

    printf("%d\n", binary_search(ints, 9, sizeof ints/ sizeof(int)));

    printf("%d\n", binary_search(ints, 3, sizeof ints/ sizeof(int)));

    return 0;

}