Insertion Sort

[cbouwkamp]

I created an insertion sort for an assignment about a year ago for a data structures and algorithms class and now when I run it the highest number in the sort comes out as a -898549384 or something like that. It didnt used to do that so I thought. I am now using visual studio 2010 could that be it? Here is the code

#include <stdio.h>
#include <stdlib.h>
#include <time.h>

void insertionSort(int array[], int last){
     int hold;
     int walker;
     int current;

     for (current = 1; current <= last; current++){
         hold = array[current];
         for (walker = current - 1; 
             walker >= 0 && hold < array[walker]; walker--){
                    array[walker + 1] = array[walker];
             }
          array[walker + 1] = hold;
     }
     return;
}

int main(int argc, char *argv[])
{
  int numbers[10];
  int i;
  
  srand(time(NULL));
  for (i = 0; i < 10; i++){
      numbers[i] = rand() % 100;
  }
  printf("Unsorted Numbers\n-------- -------\n");
  for (i = 0; i < 10; i++){
      printf("%d,", numbers[i]);
  }
  insertionSort(numbers, 10);
  printf("\nSorted Numbers\n-------- -------\n");
  for (i = 0; i < 10; i++){
      printf("%d,", numbers[i]);
  }
  system("PAUSE");	
  return 0;
}

[shacktar]

for (current = 1; current <= last; current++){
         hold = array[current];

Here, when current == last you will have overstepped the bounds of the array by one. You probably meant to do current < last.

It didnt used to do that so I thought.

It probably didn't. Overstepping array bounds produces undefined behaviour. In general, undefined behaviour presents itself like this. The program may run fine at one time but could crash the next.

[cbouwkamp]

thank you very much