Macros of functions

[littleprogrammer]

Hi there ! I have a question about macros. I've read that macros can be dangeurous and it's better to use a function than a macro. For example:

a macro like:

#define MAX(a,b) (a > b) ? a : b

is better in a function form like

int MAX (int a, int b)
{
   if (a > b)
      return a;
   else
      return b;
}

I dont't think so, I prefer macros.

[R0mai]

Why do you prefer macros?

[littleprogrammer]

It takes just one line. Are functions faster than macros ?

[R0mai]

http://www.parashift.com/c++-faq-lite/inline-functions.html#faq-9.5

[littleprogrammer]

Thanks for the link.

It's necessary to use inline functions or simple functions like MAX(a, b) ? inlines are faster ?

[R0mai]

inlines are faster ?

http://www.parashift.com/c++-faq-lite/inline-functions.html#faq-9.3

Also, I recommend reading the whole FAQ, you will learn a lot of good practices.

[Bazzy]

R0mai wrote:

Why do you prefer macros?

littleprogrammer wrote:

It takes just one line

int MAX (int a, int b) { return (a > b) ? a : b; }

[littleprogrammer]

@Bazzy: you're right, I got wrong ...

Thanks both . :)

[jsmith]

@littleprogrammer:

Just run this code and then tell me macros are better:

#include <iostream>

#define MAXIMUM( a, b ) a > b ? a : b

int main() {
    int a = 4;
    int b = 6;
    int c = MAXIMUM( a++, b );
    std::cout << a << ", " << b << ", " << c << std::endl;
}

An inline function is exactly as fast as a macro.

EDIT: removed extra semicolon at end of macro definition as pointed out by PanGalactic

[PanGalactic]

@jsmith: that trailing semicolon on the macro definition means you can't use it in a conditional.

Without this semicolon, this is always fun too:

int x = MAXIMUM(30, 11) - 20;  // x = 10?
std::cout << "x = " << x << std::endl;