CODEWITHSUNDEEP
c++arraysruntime-error
Peter Olson
Peter Olson

Reputation: 3

Why does this code cause the program to stop working?

When you run this, the line with the error comment causes the program to stop working, at least for me. It's such simple code, I am sort of baffled as to why this would cause things to break?

#include <iostream>
#include <iomanip>
#include <stdlib.h>
#include <conio.h>
#include <math.h>
#include <string.h>
#include <time.h>
#include <stdio.h>
using namespace std;

static const int ARRAY_SIZE = 100;

bool runAgain ( ) {
    char runChar;

    cout << "\n\nRun again? (Y/N)";
    cin >> runChar;
    runChar = toupper(runChar);
    if(runChar != 'Y')
        return false;

    system("cls");
    return true;
}

int main ( ) {

   int nums[ARRAY_SIZE];
   int length;
   int num, highIndex, lowIndex;

   length = sizeof(nums)/sizeof(int);
   srand((unsigned)time(NULL)); //make numbers more random

   do {

      cout << "Array contains: \n";

      for(int i = 0; i < length; i++) {
         num = rand() % 1000 + 1;

         if(i == 0)
             highIndex, lowIndex = i;
         else if(num > nums[highIndex]) //@@ ERROR occurs on this line
             highIndex = i;
         else if(num < nums[lowIndex])
             lowIndex = i;

         nums[i] = num;

         cout << num << "\n";
      }

      cout << "\nHighest Value: " << nums[highIndex] << " at index " << highIndex;
      cout << "\nLowest Value: " << nums[lowIndex] << " at index " << lowIndex;

   }while(runAgain());

   return 0;
}

The error is specifically that windows says that .cpp has stopped working and ends the run superficially. From running a debugger, I know it happens after the first iteration of the loop during the first else if in the for loop.

edit: ahh, yes the issue was the 'highIndex, lowIndex = i'. Thanks for the help

Upvotes: 0

Views: 112

Answers (1)

Jonathan Potter
Jonathan Potter

Reputation: 37122

The problem is highIndex, lowIndex = i;.

This does not, as you think, assign highIndex and lowIndex the value of i. Only lowIndex is assigned, highIndex remains uninitialised. Therefore the program crashes when you try to dereference the array using highIndex as the value could be anything.

Change your code line to:

highIndex = lowIndex = i;

Upvotes: 2

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