quick sort: idk why this program is showing error

Question

// Online C compiler to run C program online
#include <stdio.h>
int swap(int *x,int *y){
int temp;
temp=*x;
*x=*y;
*y=temp;
}
int pivot(int arr[],int first,int last)
{
int pivot=arr[first];
int left=first+1;
int right=last;
while(left<right){
while(left<right && arr[left]<pivot){
left++;
}
while(left<right && arr[right]>pivot){
right--;
}
if(right<left)//done to isolate the
break;
else
swap(&arr[left],&arr[right]);

}
swap(&arr[first],&arr[right]);
return right;
}
int quick_sort(int arr[],int first,int last)
{
int p=pivot(arr,first,last);
quick_sort(arr,p+1,last);
quick_sort(arr,first,p-1);
}
int main() {
int a[]={19,23,7,21,27,17,30,3,1,15};
int size=sizeof(a)/sizeof(a[0]);
quick_sort(a,0,size-1);
return 0;
}

Answer 1

Your quick_sort function calls itself infinitely.

When you write recursive functions, always create a base case which tells the program when the recursion must stop.