arrays and sorting in C

Question

I am writing a program for a coursework , basically its idea is to track an element in an array before sorting it and find its index after sorting.It work for numbers up to around 9999 I think but when I enter a large input as 18383833 (on the first input) the mac OS terminal gives me this error: segmentation fault : 11

here is my code :

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

void swap(int *xp, int *yp)
{
    int temp = *xp;
    *xp = *yp;
    *yp = temp;
}

// A function to implement bubble sort                                                                                                                                                                             
void bubbleSort(int arr[], int n)
{
    int i, j;
    for (i = 0; i < n-1; i++)
        // Last i elements are already in place                                                                                                                                                                    
        for (j = 0; j < n-i-1; j++)
            if (arr[j] > arr[j+1])
                swap(&arr[j], &arr[j+1]);
}

int main()
{
    int y; // 2nd INPUT : the nth order of the arriving person                                                                                                                                                     
    printf("Enter the nth order of the arriving person \n");
    scanf("%i" , & y);
    int array[y]; // array to store the values of the number of people            in queue                                                                                                                         
    int i; //loop counter                                                                                                                                                                                          
    printf("Enter the value of ticket of the first person \n");
    scanf("%i " , & array[0]);
    printf("\n");

    for(i=1 ; i<y ; i++) {
        array[i]= (31334 * array[i-1]) % 31337;
        //printf(" %i \n" , array[i]);                                                                                                                                                                             
    }

    int r; //loop counter                                                                                                                                                                                          
    bubbleSort(array , y);

    for(r=0 ; r<y ; r++) {
        printf("%d (%i) \n" ,  array[r] , r);
    }
}

Answer 1

The problem is on this line:

int array[y];

The memory is allocated on the stack, and as stack space is rather limited it blows up.

Replace it by:

int *array = malloc(y * sizeof(*array));

if (array == NULL)
{
   printf("Not enough memory\n");
   exit(1);
}

and it should work.