来个笨一点的
#include <stdio.h>
main()
{
    int a,b,c;
    int max=0;
    printf("qingshuru1");
    scanf("%d",&a);
    printf("qingshuru2");
    scanf("%d",&b);
    printf("qingshuru3");
    scanf("%d",&c);
    if(a>max)
        max==a;
    if(b>max)
        max==b;
    if(c>max)
        max==c;
    printf("max=%d",max);

   
}

==换成=，改一下

没有考虑数字相等的情况

#include <stdio.h>
int max(int x,int y,int z)
{
    if(x>y&&x>z) return x;
    else if(z>y&&z>x) return z;
    else if(y>x&&y>z) return y;
}
int main(void)
{
    int a,b,c;
    scanf("%d,%d,%d",&a,&b,&c);
    printf("\nThe max number is:%d",max(a,b,c));
    getchar();
    return 0;
}

为什么要用==

#include <stdio.h>
#include <stdlib.h>
int main()
{   int a,b,c;
    int max1,mid1,min1;
    int ag=1;
    int max(int a,int b,int c);
    int mid(int a,int b,int c);
    int min(int a,int b,int c);
   
    if(ag==1)
    {
        while(ag)
       {
           system("cls");
           printf("这是3个数字大小排序，请输入3个数字，3数中间按Enter间隔\n\n");
        scanf("%d %d %d",&a,&b,&c);
        max1=max(a,b,c);
        mid1=mid(a,b,c);
        min1=min(a,b,c);
        printf("排序完成，从大到小依次为：%d %d %d\n\n",max1,mid1,min1);
        printf("排序完成，从小到大依次为：%d %d %d\n\n",min1,mid1,max1);
        printf("输入1 Enter进入下次排序，输入非1任意键后Enter退出\n\n");
        scanf("%d",&ag);
        printf("\n\n");   
        if(ag!=1)
            break;              
        }
    }
//    return 0;
}

int max(int x,int y,int z)
{   int g;
    if(x>=y&&x>=z)
         g=x;
    if(y>=x&&y>=z)
         g=y;
    if(z>=x&&z>=y)
         g=z;                  
    return g;
 }

int mid(int x,int y,int z)
{   
    int g;
    if(x>=y&&x<=z)
         g=x;
    if(x>=z&&x<=y)
         g=x;
    if(y>=x&&y<=z)
         g=y;
    if(y>=z&&y<=x)
         g=y;
    if(z>=x&&z<=y)
         g=z;
    if(z>=y&&z<=x)
         g=z;                           
    return g;
}

int min(int x,int y,int z)
{   int g;
    if(x<=y&&x<=z)
         g=x;
    if(y<=x&&y<=z)
         g=y;
    if(z<=x&&z<=y)
         g=z;
    return g;                        
}

[此贴子已经被作者于2016-2-3 15:16编辑过]