title: string copy using pointer as a argument of function.
body: <pre><code>#include &lt;stdio.h&gt;
  void stringcopy(char *, char *);
  
  int main(void) 
  {
  
     char *a="akash";
     char *b;
     stringcopy(a,b);
     printf("%s",b);//why this is null? 
     return 0;
     }
   void  stringcopy(char*a,char*b)
  {
       b=a;
       printf("%s\n",b);// it is not null
  }
  </code></pre>
  
  <blockquote>
    <p>Blockquote
    in a function stringcopy ,i am getting output right. but after call i am getting null in main.why 
        it is happening?please explain?</p>
  </blockquote>