#include<stdio.h>
void string(char past[],char now[]) 
{
int i=0;
 while(past[i]!='\0')
  {now[i]=past[i];
i++;
  }
 now[i]='\0';
}
main()
{char m[]="we are happy.";
 char n[]="you are unhappy.";
printf("m=%s\n",m);                   /*原来字符串m*/
printf("n=%s\n",n);                  /*原来字符串n*/
 string(m,n);
printf("m=%s\n",m);/*函数调用后字符串m*/
printf("n=%s\n",n);                  /*函数调用后字符串n*/
 }
