Quick Sort- Algorithm

#include <stdio.h>
#include<stdlib.h>
#include<time.h>
#define size 20000
int a[size];
void quickSort( int[], int, int);
int partition( int[], int, int);
void main()
{
    int i;
    clock_t begin,end;
    double time_spent;
    for(i=0;i<size;i++)
    {
        a[i]=rand()%100;
    }
    begin=clock();
    quickSort( a, 0,size-1);
    end=clock();
    printf("\n\nSorted array is:  ");
    time_spent=(double)(end-begin)/CLOCKS_PER_SEC;
    printf("\nSorted array:\n");
    for(i=0;i<size;i++)
    {
        printf("%d ",a[i]);
    }
    printf("\nTime Elapsed:%f\n",time_spent);

}
void quickSort( int a[], int front, int rear)
{
   int j;

   if( front < rear )
   {
       j = partition( a, front, rear);
       quickSort( a, front, j-1);
       quickSort( a, j+1, rear);
   }

}
int partition( int a[], int front, int rear) {
   int x, i, j, temp;
   x = a[front];
   i = front; j = rear+1;

   while( 1)
   {
    do ++i;
    while( a[i] <= x && i <= rear );
    do --j;
    while( a[j] > x );
    if( i >= j )
        break;
    temp = a[i];
    a[i] = a[j];
    a[j] = temp;
   }
   temp = a[front];
   a[front] = a[j];
   a[j] = temp;
   return j;
}