Date: Tue, 3 Oct 2000 10:52:42 -0700
From: Hannah C. Tang <hctang@cs.washington.edu>
Newsgroups: uwash.class.cse142.bboard
Subject: Re: assign "=" function

This experiment with #define's is a good reminder to all that the
syntax for #define's is slightly different than the syntax for, say,
assignment for variables.

When dealing with #define'd constants, you should assume that your
#define'd constant will be *exactly* replaced in your program with its
associated constant value (because #define's are a simply a
text-substitution made by the pre-processor [you may want to review the
slides on compilation if this is an unfamiliar term]).

Assume you had the following program:

  #define FOO = 4;

  int main(void) {
      int bar = FOO + 3;
      printf("bar is %d\n", bar);
      return 0;
  }


Notice the incorrect syntax for the #define.  This means that the compiler
believes that your program actually looks like:

  int main(void) {
    int bar = = 4;  + 3;
    printf("bar is %d\n", bar);
    return 0;
  }


Which you can see is incorrect.  The correct way of defining FOO to be 4
would be:

  #define FOO 4

  int main(void) {
      int bar = (FOO) + 3;
      printf("bar is %d\n", bar);
      return 0;
  }

Because the text '4' will replace the text 'FOO' wherever it occurs in 
your program, this will yield the following program:

  int main(void) {
      int bar = (4) + 3;
      printf("bar is %d\n", bar);
      return 0;
  }

Hannah

----- Original Message -----
Date: Mon, 2 Oct 2000 23:44:29 -0700
From: 
To: 
Newsgroups: uwash.class.cse142.bboard
Subject: Re: assign "=" function

The Line is:

	SUBTOTAL = (double)GALLEONS * EUROS_PER_GALLEON;

and three such like it... but the problem wasn't with the above, I
discovered, I typed in my #define incorrectly:


#define EUROS_PER_GALLEON 60.0

I had entered as 
#define EUROS_PER_GALLEON = 60.0;

which is incorrect...

Thanks!