Zugg Software :: View topic

Apprentice Joined: 29 May 2002 Posts: 121

Need some clarification between the two different type of expressions.

I know in C and Java, = expression usually translates to an assignment statement.

I also know == is used in comparison.

So, I was looking in the manual for details on how either is used in Zmud and can only find about the = expression.

Any comments on ==?

Thanks.

Enchanter Joined: 10 Oct 2000 Posts: 656 Location: USA

I'm not familar with the use of == in zmud. = can be an assignment if used like variablex='something' or = can be a compairison if used within a IF like #if (@var1='something') {dosomething}

MASTER Joined: 28 Nov 2000 Posts: 4817 Location: USA

The only difference I'm aware of, through version 6.62, is that = is documented and == is not. Otherwise, they seem to be interchangeable. I recommend using the documented one.

Posted: Wed Sep 24, 2003 7:46 pm

As LightBulb mentioned, in an #IF or %if expression, == is the same as =. I added == so that people used to C wouldn't have any trouble, but = is the documented equality test in zMUD.

The use of = as assignment within an IF statement in C (and other C-based languages) is one of the things that I've always hated about C. Being able to change the value of a variable within an expression test produces hard-to-support code in my opinion. Even though Pascal still distinguishes between the two operations using := for assignment and = for equality test, at least they don't allow := to be used within an expression.

In zMUD, the issue is somewhat historical. For a long time, zMUD did not have any assignment operator at all. The = was always used for equality testing, the == was added for C users, and #VAR was used for assignment. Then, in one of the later versions of zMUD, the A=B syntax was added as a shortcut for "#VAR a b" to provide assignment like in other languages. I could have chosen to implement this as A:=B like in Pascal, but went with the simplier syntax to parse.

Probably more than you wanted to know about = in zMUD Smile