#include<stdio.h>
int max(int,int);
int main()
{
    int a,b;
    printf("input two inergers:");
    scanf("%d %d",&a,&b);
    printf("The max integer is %d.\n",man(a,b));
    return 0;
}
int max(int num1,int num2)
{
    if(num1>num2)
    {
        return num1;
    }
    else
    {
        return num2;
    }
}

printf里的函数调用max(a,b)写成了man

#include<stdio.h>
int max(int,int);
int main()
{
    int a,b;
    printf("input two inergers:");
    scanf("%d %d",&a,&b);
    printf("The max integer is %d.\n",man(a,b));             //man(a,b)? 这是。。。。 
    return 0;
}
int max(int num1,int num2)
{
    if(num1>num2)
    {
        return num1;
    }
    else
    {
        return num2;
    }
} 

#include<stdio.h>
int max(int num1,int num2){
    return num1>num2?num1:num2;
} 
int main()
{
    int a,b;
    printf("input two inergers:");
    scanf("%d %d",&a,&b);
    printf("The max integer is %d.\n",max(a,b));               
    return 0;
}

楼上换头像了耶

printf("The max integer is %d.\n",man(a,b))/max(a,b)写错了