快速排序C语言实现

# include <stdio.h>

int FindPos(int * a, int low, int high);
void QuickSort(int * a, int low, int high);

int main(void)
{
    int a[6] = {-2, 1, 0, -985, 4, -93};
    int i;

    QuickSort(a, 0, 5); //第二个参数表示第一个元素的下标  第三个参数表示最后一个元素的下标
    
    for (i=0; i<6; ++i)
        printf("%d  ", a[i]);
    printf("\n");

    return 0;
}

void QuickSort(int * a, int low, int high)
{
    int pos;

    if (low < high)
    {
        pos = FindPos(a, low, high);
        QuickSort(a, low, pos-1);
        QuickSort(a, pos+1, high);
    }    
}

int FindPos(int * a, int low, int high)
{
    int val = a[low];

    while (low < high)
    {
        while (low<high  && a[high]>=val)
            --high;
        a[low] = a[high];

        while (low<high && a[low]<=val)
            ++low;
        a[high] = a[low];
    }//终止while循环之后low和high一定是相等的

    a[low] = val; 

    return high; //high可以改为low, 但不能改为val 也不能改为a[low]  也不能改为a[high]
}