#include<stdio.h>
#include<string.h>
int main()
{ 
   void swap(char* , char* );	
   char a[20];
   char b[20];
   char c[20];
   printf("please enter three strings:");
   gets(a);//获得字符串
   gets(b);
   gets(c);
   if(strcmp(a , b)>0) swap(a , b);
   if(strcmp(a , c)>0) swap(a , c);
   if(strcmp(b , c)>0) swap(b , c);
   printf("The order is: %s,%s,%s\n",a,b,c);
   return 0;	
} 
void swap(char *pt1, char *pt2)//交换字符串
{ 
	char pt[20];
	strcpy(pt , pt1);
	strcpy(pt1 , pt2);
	strcpy(pt2 , pt);