indent-region to indent comments

[Suhas Pai]

If I mark a region and indent it, I find that it
only idents the source lines and not the comment lines.
If my comment-column is set, why the indenting skips
comments?  This will save me ton of time having to
do each one using "esc ;".  I could always write a macro
but I don't know how to bind a macro to a key. 

Please help.

Before:
-------

int main(int argc, char **argv)
{
   int a = 5;           // first comment
   double b = 5.0;   // second comment
   long c = 3;   // third comment
   b = a + c; // so as not to get unused variable error

   return 0;
}

Expect after ident-region:
--------------------------
int main(int argc, char **argv)
{
   int a = 5;         // first comment
   double b = 5.0;    // second comment
   long c = 3;        // third comment
   b = a + c;         // so as not to get unused variable error

   return 0;
}


Thanks,
Suhas