[Dev-C++] Exit Codes

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

Dear Users,

1. Every time I finish a code without problems the final code is return 0
for an int main()
   function;
2. But, if exists inside the code a primary condition for the code run I use
a piece of
   code like the following:
   ...
   char *ptr;

   ptr=malloc(10*sizeof(char));
   if(!ptr)
   {
      printf("no mem");
      exit(1);
   }
   ...
   That is, I scape in advance of the execution because lack of resources;
3. It´s my interest to change the zero of the 1 statement for an
EXIT_SUCCESS stdlib.h constant;
4. I couldn´t find an constant for 1 in an EXIT style;
5. I think I can´t change an exit(1) for an exit(EXIT_FAILURE) because this
constant is equal to
   -1;

My Questions:
A) Can I make the #3 substitution?
B) Is that true the #4 statement?
C) Can I make the #5 substitution?

Regards
Andre