Passing define int to function as an argument

Question

I don't understand why the following code won't compile:

#include <iostream>
#define SHORT_NAME 4;

int func(int arg)
{
    return arg;
}

int main()
{
    return func(SHORT_NAME); // Error: expected a ')'
}

Should I be using const int SHORT_NAME = 4 on line 2 instead?

Answer 1

Remove the semi-colon from the macro SHORT_NAME as after preprocessing it is expanded to:

 return func(4;);

Or use const int as you suggest in the question. See "static const" vs "#define" vs "enum" for a discussion on macros vs const.

Answer 2

The preprocessor expands the MACRO name. So this:

return func(SHORT_NAME);  

becomes this:

return func(4;); 

that is definitely a syntax error, isn't?

So if you define the MACRO without ; then it will work:

#define SHORT_NAME 4  //without ;

---

Should I be using const int SHORT_NAME = 4 on line 2 instead?

YES. Go for it. Macros are evil, anyway (in most cases).

Answer 3

You don't need the semicolon in your define. Write this instead

#define SHORT_NAME 4

But using const int is definitely a better choice when using C++.