这个我写了一个,你看下:
#include <stdio.h>

void main()
{
    float num,max;

    num = max = 0;
    do
    {
        printf("please input number:");
        scanf("%f",&num);
        if(num <= 0.0) break;
        if(num > max)
            max = num;
    }while(1);

    printf("the max is:%f\n",max);
}
我的算法是:对每个输入的数做一个判断就好了啊!

#include<stdio.h>
int main()
{
    double x,max;
        printf("Enter a number:");
        scanf("%lf",&x);
        max=x;
        do{
            printf("Enter a number:");
            scanf("%lf",&x);
            if(max<x) max=x;
        }
        while(x>0);
        printf("The largest number entered was %f\n",max);
        return(0);
}