Simple C++ program, access violation error...doesn't make sense to me?

[PingSpike]

I'm sure this is something stupid, but it doesn't make sense to me. I'm trying to find the mode in a list of values passed to a function. It isn't complete yet, but once I get to the inner for loop I get an access violation message at run time with VC++. If I hover over the variables i and truelength at this point it shows "766" which I assume is the current value. Which makes no sense to me at all.

#include <iostream>
using namespace std;

void printarray (int *list, int length)
{
    int *candidates;
    int *counts;
    candidates = new int[length]; //must be some problem with these...can't write to them?
    counts = new int[length]; //??
    //int candidates [10];
    //int counts [10];
    int truelength = 0;

    int choice = 0;

    //candidates[0] = list[0]; //add first item to list of candidates
    //counts[0] = 1; // set that items count to 1

    for (int n=0; n<length; n++)
    {
        for (int i=0; i<=truelength; i++)
        {
            if ( i == truelength ) // no matches found, this is new
            {
                candidates[truelength] = list[n];
                counts[truelength] = 1;
                truelength = truelength + 1; //update count
            }
            else
            if ( list[n] == candidates[i] ) // we found a match in the current list
            {
                counts[i] = counts[i] + 1;
                break; //i = truelength; // force loop escape
            }
        }

    }

    for (int j=1; j<truelength; j++)
    {
        if (counts[j] > counts[choice])
            choice = j;
    }


   // cout << *(list+n) << ",";
  cout << candidates[choice];
  cin >> choice;
  //clean up
  delete [] candidates;
  delete [] counts;
}

int main ()
{
    int inputs[8] = { 1, 2, 3, 4, 5, 8, 9, 9 };
    int length = 8;

  printarray(inputs, length);
  return 0;
}

 

[Markbnj]

The loop counter i starts out as 0. The variable truelength starts out as 0. In that condition the inner loop will increment both i and truelength by 1, meaning they will always be equal and the top part of your conditional in the inner loop will always execute, meaning i and truelength increment in lockstep and you keep writing to candidates[] and counts[] until you overrun the original 32 byte length of these arrays and then continue until you stomp something you shouldn't, causing the error.

 

[PingSpike]

Thanks Markbnj. Pretty obvious now. I didn't break out of the loop when adding a new item to the list and since the true length kept getting incremented it just repeated that condition. Durr.