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二分查找算法通常用于在有序数组中查找特定元素。以下是使用Python、Java和C++实现的二分查找算法的示例代码。

Python:

def binary_search(arr, x):
    low = 0
    high = len(arr) - 1
    while low <= high:
        mid = (low + high) // 2
        if arr[mid] == x:
            return mid
        elif arr[mid] > x:
            high = mid - 1
        else:
            low = mid + 1
    return -1
 
# 示例使用
arr = [2, 3, 4, 10, 40]
x = 10
 
# 函数调用
result = binary_search(arr, x)
print(result)  # 输出元素的索引，未找到返回-1

Java:

public class BinarySearch {
    public static int binarySearch(int[] arr, int x) {
        int low = 0;
        int high = arr.length - 1;
        while (low <= high) {
            int mid = (low + high) / 2;
            if (arr[mid] == x) {
                return mid;
            } else if (arr[mid] > x) {
                high = mid - 1;
            } else {
                low = mid + 1;
            }
        }
        return -1;
    }
 
    // 示例使用
    public static void main(String[] args) {
        int[] arr = {2, 3, 4, 10, 40};
        int x = 10;
 
        // 函数调用
        int result = binarySearch(arr, x);
        System.out.println(result);  // 输出元素的索引，未找到返回-1
    }
}

C++:

#include <iostream>
#include <vector>
 
int binarySearch(const std::vector<int>& arr, int x) {
    int low = 0;
    int high = arr.size() - 1;
    while (low <= high) {
        int mid = (low + high) / 2;
        if (arr[mid] == x) {
            return mid;
        } else if (arr[mid] > x) {
            high = mid - 1;
        } else {
            low = mid + 1;
        }
    }
    return -1;
}
 
int main() {
    std::vector<int> arr = {2, 3, 4, 10, 40};
    int x = 10;
 
    // 函数调用
    int result = binarySearch(arr, x);
    std::cout << result << std::endl;  // 输出元素的索引，未找到返回-1
    return 0;
}

以上代码实现了二分查找算法，在有序数组中查找特定元素的索引。如果找到，返回元素的索引；如果未找到，返回-1。