```c
#include<stdio.h>
void copy(char *p,char *q);
int main()
{
char *a="I am a student";
char *b="I am a teacher";
printf("a is %s\nb is %s\n",a,b);
copy(a,b);
printf("\nnew a is %s\nb is %s\n",a,b);
return 0;
}
void copy(char *p,char *q)
{
int i=0;
while(*p!='\0')
{
*p=*q;
p++;
q++;
}
*p='\0';
}
```