quickly sort

#include<stdio.h>
#include<stdlib.h>
#define size 9
void alter(int *a,int*b)
{
    int temp;
    temp=*a;
    *a=*b;
    *b=temp;
}
void sort(int *low,int *high)
{
    int i;

    int *left,*right;
    left = low+1;
    right = high;
    if(right-left == 0)
    {
        if(*low>*left){
            alter(low,left);
        }
    }

    while(right- left > 0)
    {
        if(*left>*right){
            alter(left,right);
        }
        if(*right>*low){
            right--;
        }
        if(*left<*low){
            left++;
        }
    }

    if( high - low <= 1)return;
    sort(low, right);
    sort(right, high);
}
int main()
{
    int arr[size+1]={3,6,5,4,8,1,7,4,11,100},i;
    sort(arr,arr+size);
    for(i=0;i<size;i++)
        printf("%d ",arr[i]);
    printf("\n");
    return 0;
}