C++分段错误(核心转储)和使用结构

Question

我有一个编写maxSubArray算法的任务。它大部分都在工作，但我在返回结构时遇到了一些问题。

以下是相关文件（对不起，文字墙，但我不确定如何指出此错误）：

main.cpp

#include <iostream>
#include "./MaxSubarray.h"
using namespace std;
#define TEST(test) { 
  testNum++; 
  if (!(test)) { 
    cerr << "Test " << testNum << " failed" << endl; 
    numFails++; 
  } 
}
int runTests() {
  int numFails = 0;
  int testNum = 0;
   {
     //          0   1   2*  3  4   5
     int A[] = { 1, -4, 14, -2, 3, -1 };
     Result r = findMaxCrossingSubarray(A, 0, 2, 5);
     Result c(2, 4, 15);
     TEST(r == c);
   }
   {
     //          0  1   2  3*  4   5  6
     int A[] = { 0, 5, -4, 1, -2, -3, 6 };
     Result r = findMaxCrossingSubarray(A, 0, 3, 6);
     Result c(1, 6, 3);
     TEST(r == c);
   }
   {
     //          0  1   2  3*  4   5  6
     int A[] = { 0, 5, -4, 1, -2, -3, 5 };
     Result r = findMaxCrossingSubarray(A, 0, 3, 6);
     Result c(1, 6, 2);
     TEST(r == c);
   }
   {
     int A[] = { 13, -3, 4 };
     Result r = findMaxSubarray(A, 0, 2);
     Result c(0, 2, 14);
     TEST(r == c);
   }
   {
     int A[] = { 13, 4, -3 };
     Result r = findMaxSubarray(A, 0, 2);
     Result c(0, 1, 17);
     TEST(r == c);
   }
   {
     int A[] = { -3, 4, 13 };
     Result r = findMaxSubarray(A, 0, 2);
     Result c(1, 2, 17);
     TEST(r == c);
   }
   {
     int A[] = { 4, -3, 13 };
     Result r = findMaxSubarray(A, 0, 2);
     Result c(0, 2, 14);
     TEST(r == c);
   }
   {
     int A[] = { 4, -3, -13, 5, 3 };
     Result r = findMaxSubarray(A, 0, 4);
     Result c(3, 4, 8);
     TEST(r == c);
   }
   {
     int A[] = { 4, 3, -13, -5, 3 };
     Result r = findMaxSubarray(A, 0, 4);
     Result c(0, 1, 7);
     TEST(r == c);
   }
   {
     int A[] = { -4, 4, -3, 5, -3 };
     Result r = findMaxSubarray(A, 0, 4);
     Result c(1, 3, 6);
     TEST(r == c);
   }
   {
     int A[] = { 13, -3, -25, 20, -3, -16, -23, 18, 20, -7, 12, -5, -22, 15, -4, 7 };
     Result r = findMaxSubarray(A, 0, 15);
     Result c(7, 10, 43);
     TEST(r == c);
   }

  const int numSuccesses = testNum - numFails;
  cout << numSuccesses << "/" << testNum << " tests succeeded" << endl;
  return numFails;
}
int main() {
  // TODO: Add test code as necessary.
  // This file will NOT be submitted, though!
  return runTests();
}

MaxSubarray.cpp

#include "./MaxSubarray.h"
#include <iostream>
// Provides floor, ceil, etc.
#include <cmath>
#include <climits>
using namespace std;
//Kalen Williams
//27 January 2017
Result findMaxCrossingSubarray(int* array, int low, int mid, int high){
    int leftSum = INT_MIN;
    int sum = 0;
    int maxLeftIndex;
    for(int i = mid; i >= low; i--){
        sum = sum + array[i];
        if(sum > leftSum){
            leftSum = sum;
            maxLeftIndex = i;
        }
    }
    int rightSum = INT_MIN;
    sum = 0;
    int maxRightIndex;
    for(int j = mid + 1; j <= high; j++){
        sum = sum + array[j];
        if(sum > rightSum){
            rightSum = sum;
            maxRightIndex = j;
        }
    }
    int totalSum = leftSum + rightSum;
    return Result(maxLeftIndex, maxRightIndex, totalSum);
}
Result findMaxSubarray(int* array, int low, int high){
    if(high = low){
        return Result(low, high, array[low]);
    }
    else{
        int mid = (low + high) / 2;
//
        Result leftArray = findMaxSubarray(array, low, mid);
        Result rightArray = findMaxSubarray(array, mid + 1, high);
        Result crossArray = findMaxCrossingSubarray(array, low, mid, high);
        if(leftArray.sum >= rightArray.sum && leftArray.sum >= crossArray.sum){
            return leftArray;
        }
        else if(rightArray.sum >= leftArray.sum && rightArray.sum >= crossArray.sum){
            return rightArray;
        }
        else{
            return crossArray;
        }
//
    }
}

代码按原样运行，我通过了前 3 个测试，因为我的findMaxCrossingSubarray有效，但是，当我取消注释代码时findMaxSubArray出现错误

分段故障（核心转储）

我对这个问题做了相当多的研究，知道这意味着我正在尝试引用尚未分配给程序的内存，我只是不确定如何缩小问题范围。我尝试使用 -Wall 进行编译，但这给了我一堆各种错误，这些错误似乎都与此无关。

Answer 1

如果没有看到头文件，我无法确定这是导致 Seg 错误的原因，但您在findMaxSubarray的第一行有一个错误：

if (high = low) {

你显然是说high == low.您应该已经收到一些编译器警告。如果你是一个"常量纳粹"，编译器会抓住这个......（即和错误而不是警告）：我的意思是，当然，将const int high和const int low放在函数定义中（声明中忽略了const，顺便说一句）。