C++递归计算数组元素和触发Segmentation fault问题求助

开发者阿泽

2026-5-14

Fixing the Segmentation Fault in Your Recursive Array Sum Function

Hey there! Let's break down why your code is hitting a segmentation fault and how to fix it.

The Root Cause

The problem lies in how you're splitting the array for the right recursive call. Let's look at this line:

int y = findSum(arr, mid, e);

When your current interval [b, e] has b != e but they're adjacent (like b=0, e=1), mid will be (0+1)/2 = 0. This means the right call becomes findSum(arr, 0, 1)—exactly the same as the original call. You've created an infinite recursion loop! Each recursive call adds a new frame to the stack, and eventually, you run out of stack space, triggering a segmentation fault.

The Fix

To fix this, you need to split the array into non-overlapping, shrinking intervals. Change the right recursive call to start at mid + 1 instead of mid:

int y = findSum(arr, mid + 1, e);

This way, each recursive call works on a smaller subarray. When b == e, you hit the base case and return the single element, stopping the recursion.

Corrected Full Code

Here's the fixed version of your code:

#include <iostream>
using namespace std;

int findSum(int arr[], int b, int e) {
    if (b == e) 
        return arr[b];
    else {
        int mid = (b + e) / 2;
        int x = findSum(arr, b, mid);
        int y = findSum(arr, mid + 1, e);
        return x + y;
    }
}

int main() {
    int arr[] = {1, 6, 3, 10, 11, 4, 5, 9, 15, 2};
    cout << findSum(arr, 0, 9) << endl;
    return 0;
}

A couple of small notes beyond the fix:

I replaced <bits/stdc++.h> with <iostream> since that's all you need here—it's better practice to include only necessary headers.
Removed system("pause") as it's Windows-specific and not needed for the program to function correctly.