网上关于这一问题的写法其实很多，但是很多方法不具有实际的应用价值（比如单纯使用if和else语句写出六种可能做判别），当然这也不失为一种思路，这里仅罗列出三种具有代表性的处理方法（三目运算法、IF比较法、和IF比较的指针写法）

//if语句依次比较大小排序
#include <stdio.h>
int compare(int x,int y,int z)
{
    int t=0;
    if(x<y)
    {
        t=x;x=y;y=t;
    }
    if(y<z)
    {
        t=y;y=z;z=t;
    }
    if(x<y)
    {
        t=x;x=y;y=t;
    }
    printf("the number from big to small is\n %d %d %d \n",x,y,z);
}

int main()
{
    int a,b,c;
    printf("please input three numbers \n");
    scanf("%d %d %d",&a,&b,&c);
    compare(a,b,c);
    return 0;
}

//三目运算比大小
#include <stdio.h>

int max(int x,int y,int z)
{
    int max=0;
    max=x>y?x:y;
    max=max>z?max:z;
    return max;
}

int smaller(int x,int y,int z)
{
    int smaller=0;
    smaller=x<y?x:y;
    smaller=smaller<z?smaller:z;
    return smaller;
}

int middle(int x,int y,int z)
{
    int middle=0;
    middle=x+y+z-smaller(x,y,z)-max(x,y,z);
    return middle;
}

int main()
{
    int a,b,c;
    printf("please input three numbers \n");
    scanf("%d %d %d",&a,&b,&c);
    printf("the number from max to small is %d %d %d \n",max(a,b,c),middle(a,b,c),smaller(a,b,c));
    return 0;
}

//指针的使用与指针解引用
#include <stdio.h>
int compare(int *x,int *y,int *z)
{
    int t;
    if(*x<*y)
    {
        t=*x;*x=*y;*y=t;
    }
    if(*y<*z)
    {
        t=*y;*y=*z;*z=t;
    }
    if(*x<*y)
    {
        t=*x;*x=*y;*y=t;
    }
    printf("the number from big to small is\n%d %d %d \n",*x,*y,*z);
}


int main()
{
    int a,b,c;
    printf("please input three numbers \n");
    scanf("%d %d %d",&a,&b,&c);
    compare(&a,&b,&c);
    return 0;
}