#include<stdio.h>


main()
{
    int a[20];
    int i,c,n,temp,h,l=0;
    printf("Input the length of the array(<20):");
    scanf("%d",&n);
    printf("\nInput %d datas:",n);
    for(i=0;i<n;i++)
    {
        scanf("%d",&a[i]);
    }
    printf("\nThe array are:");
    for(i=0;i<n;i++)
    {
        printf("%4d",a[i]);
    }
    h=n-1;
    temp=a[0];

    while(l<h)
    {
        while(temp<a[h])
            h=h-1;
        if(a[l]>a[h])
        {
            c=a[l];
            a[l]=a[h];
            a[h]=c;
            l=l+1;
        }
        else
            h=h-1;
        if(a[h]<a[l])
        {
            c=a[l];
            a[l]=a[h];
            a[h]=c;
            h=h-1;
        }
        else
            l++;
    }

    printf("\n\nThe array after quicksort are:");
    for(i=0;i<n;i++)
    {
        printf("%4d",a[i]);
    }
    printf("\n\n");
}

谢大神，自己后来在while那改了也可以了。
    while(l<h)
    {
        if((a[l]>temp)||(a[h]<temp))
        {
            c=a[l];
            a[l]=a[h];
            a[h]=c;
        }
        while(a[l]<temp)
        {
            l++;
            break;
        }
        while(a[h]>temp)
        {
            h--;
            break;
        }
       }