程序代码：

#include<stdio.h>
float max2(float X,float y)
{
    float max;
    if (x>=y)
    max=x;
    else
    max=y;
    printf("the max is:%f",max);
}
int main()
{
    fioat a,b;
    printf("input two real numbers:\n");
    scanf("%f%f",&a,&b);
    max2(a,b);
    return 0;
    }