str rev using fn pointer with local

#include<string.h>
#include<stdlib.h>
#include<stdio.h>
/* function prototype */
char *rev(char*);
//int strlen(char*);
int main()
{
char a[10]="selva";
char *p;
/* function call*/
p=rev(a);
printf("rev e string id %s\n",p);
return 0;
}
/* function defination*/
char *rev(char *q)
{
int l=0;
static char b[10];
char *r;
r=b;
l=strlen(q);
q=q+(l-1);
while(l>=0)
{
*r=*q;
r++;
q--;
l--;
}
return r;
}