折半查找—写代码实现在整型有序数组中查找想要的数字，找到了返回下标，找不到返回-1.

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写代码可以在整型有序数组中查找想要的数字，找到了返回下标，找不到返回-1.（折半查找）

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程序代码如下：

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#include <stdio.h>

int binary_search(int arr[], int key,int sz)
{
    int left = 0;
    int right = sz - 1;
    while (left <= right)
    {
        int mid = left + ((right - left) >> 1);
        if (key > arr[mid])
        {
            left = mid + 1;
        }
        else if (key < arr[mid])
        {
            right = mid - 1;
        }
        else
        {
            return mid;
        }
    }
    return -1;
}
int main()
{
    int arr[] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };
    int key = 8;
    int sz = sizeof(arr) / sizeof(arr[0]);
    int ret = binary_search(arr,key,sz);
    if (ret == -1)
    {
        printf("找不到\n");
    }
    else
    {
        printf("找到了：%d\n", ret);
    }
    return 0;
}

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程序运行结果如下：

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