[Dev-C++] Correct use of pointers

[<and...@su...>]

Gentlemen,

   Even in the Ritchie´s books sometimes I fount .C codes using "wild
pointers" or something
like:
****************
void main()
{
   int *p, a, b;

   a=2;
   b=3;
   *p = a + b;

   ...
}
****************
But... in large programs we can have problems.

   Would I be corret, allways, if I use insted a code like:
*********************
#include <stdlib.h> /* or alloc.h */

void main()
{
   int *p, a, b;

   p=malloc(1*sizeof(int));
   a=2;
   b=3;
   *p = a + b;
   ...
   free(p);
}
******************
1. It´s not necessary, but is it tecnically correct?
2. Is there any point, where the previous memory allocation is mandatory?

Thanks
Andre