C++ 实现二分查找

以下是C++实现二分查找的代码示例：

#include <iostream>
using namespace std;

int binarySearch(int arr[], int left, int right, int x) {
    while (left <= right) {
        int mid = left + (right - left) / 2;

        // 如果 x 在中间
        if (arr[mid] == x)
            return mid;

        // 如果 x 大于中间元素，则在右侧子数组中查找
        if (arr[mid] < x)
            left = mid + 1;

        // 如果 x 小于中间元素，则在左侧子数组中查找
        else
            right = mid - 1;
    }

    // 如果未找到 x，则返回 -1
    return -1;
}

int main() {
    int arr[] = { 2, 3, 4, 10, 40 };
    int n = sizeof(arr) / sizeof(arr[0]);
    int x = 10;
    int result = binarySearch(arr, 0, n - 1, x);
    (result == -1) ? cout << "Element is not present in array"
                   : cout << "Element is present at index " << result;
    return 0;
}