My code doesn't run the same way on different compilers-CodePudding

first of all, I'm just starting to learn C programming on my own so please don't be mad if I'm explaining or doing something wrong, I tried to search similar question to my problem on StackOverflow but I couldn’t find one so please if I'm doing something wrong, take it easy on me I'm only trying to learn.

I have an issue I can't understand, I wrote a sorting list program using the Insertion sort algorithm, that runs differently on different compilers. when I enter only positive numbers everything works smoothly but if I add some negatives numbers, depending on the compiler, it sometimes works and sometimes does not work at all/ prints a weird result

#include <stdio.h>
#include <string.h>

int main()
{

  // gathering sources for sorting an array:
  int myArray[5];
  int count = 1;
  for (int arrayIndex = 0; arrayIndex < 5; arrayIndex  )
  {
  
    printf("\nEnter the #%d array element: ", count);
    scanf(" %d", &myArray[arrayIndex]);
    count  ;
  }

  // calculate the last array index 
  int myInt = myArray[0];
  int arrayLength = ((sizeof(myArray)) / (sizeof(myInt))) - 1;

  // printing the unsorted array
  printf("\nthe array was: ");
  for (int i = 0; i <= arrayLength; i  )
  {
    printf(" %d ", myArray[i]);
  }
 
 // sorting the array using insertion sorting algorithm:

  for (int index = 1; index <= arrayLength; index  )
  {
    int numberCheck = index;
    while (index >= 1 && myArray[numberCheck] < myArray[numberCheck - 1])
    {
      // swap the places:

      int temp;
      temp = myArray[numberCheck];
      myArray[numberCheck] = myArray[numberCheck - 1];
      myArray[numberCheck - 1] = temp;

      // move the next element
      numberCheck--;
    }
  }
  // printing the sorted array:
  
  printf("\nthe sorted array is now: ");
  for (int i = 0; i <= arrayLength; i  )
  {
    printf(" %d ", myArray[i]);
  }

  return 0;
}

for example if I enter (0,-2,-4,12,5) on C Online Compiler - Programiz I get this result :

the array was:  0  -2  -4  12  5 
the sorted array is now:  -4  -2  0  5  12

but if I enter the same exact code on the Vscode Zsh compiler (I'm using a MacBook and to my knowledge, I didn't change anything on the compiler settings) I get the result :

the array was:  0  -2  -4  12  5 
the sorted array is now:  5  6

CodePudding user response：

I tested out your code and found a few areas where processing of array elements was going out of bounds. Some places, the value of the index was -1 and some places the value was equal to the array length value (e.g. index values that equate to myArray[5] which again is out of bounds).

Following is a copy of your code with a bit of cleanup to illustrate some usual and customary methods for processing "for" loops and processing arrays.

#include <stdio.h>
#include <string.h>

int main()
{

    // gathering sources for sorting an array:
    int myArray[5];
    int count = 1;
    for (int arrayIndex = 0; arrayIndex < 5; arrayIndex  )
    {

        printf("\nEnter the #%d array element: ", count);
        scanf(" %d", &myArray[arrayIndex]);
        count  ;
    }

    // calculate the last array index
    int myInt = myArray[0];
    int arrayLength = ((sizeof(myArray)) / (sizeof(myInt)));  /* Omittted the subtraction of 1 */

    // printing the unsorted array
    printf("\nthe array was: ");
    for (int i = 0; i < arrayLength; i  )                     /* Set loop test to be less than array length */
    {
        printf(" %d ", myArray[i]);
    }

// sorting the array using insertion sorting algorithm:

    for (int index = 1; index < arrayLength; index  )
    {
        int numberCheck = index;
        //while (index >= 1 && myArray[numberCheck] < myArray[numberCheck - 1])     /* This line of code was allowing numberCheck - 1 to be less than zero */
        while (numberCheck > 0 && myArray[numberCheck] < myArray[numberCheck - 1])  /* Revised version of the test */
        {
            // swap the places:
            int temp;
            temp = myArray[numberCheck];
            myArray[numberCheck] = myArray[numberCheck - 1];
            myArray[numberCheck - 1] = temp;

            // move the next element
            numberCheck--;
        }
    }
    // printing the sorted array:

    printf("\nthe sorted array is now: ");
    for (int i = 0; i < arrayLength; i  )       /* Revised this to not go out of bounds */
    {
        printf(" %d ", myArray[i]);
    }
    printf("\n");

    return 0;
}

It appears in the program that you are attempting set up for loop and range testing based on a range of "1" to "array length"; whereas, the usual range processing is from "0" to "less than array length". When I did those bits of cleanup, I was able to acquire a properly sorted array from the five values entered.

@Una:~/C_Programs/Console/Sorting/bin/Release$ ./Sorting 

Enter the #1 array element: 700

Enter the #2 array element: 343

Enter the #3 array element: 2

Enter the #4 array element: 58

Enter the #5 array element: 400
Array length: 5

the array was:  700  343  2  58  400 
the sorted array is now:  2  58  343  400  700

Note the comments I added to hopefully clarify bits for you. Try that out and see if it meets the spirit of your project.