#include <stdio.h>
int main()
{void copy_string(char from[], char to[]);
 char a[]="I am a teacher.";
 char b[]="you are a student.";
 printf("string a=%s\nstring b=%s\n",a,b);
 printf("copy string a to string b:\n");
 copy_string(a,b);
 printf("\nstring a=%s\nstring b=%s\n",a,b);  
 return 0;
}

void copy_string(char from[], char to[])
{ int i=0;
   while(from[i]!='\0')
     {to[i]=from[i];i++;}
   to[i]='\0';
 }