Question

Code:

#include <iostream>

using namespace std;

#define ADD(x,y)  ((x)+(y))

int main( int argc, char** argv )
{
    cout << ADD(1,2,) << endl;
    return 0;
}

Compiler output:

1>Compiling…
1>main.cpp
1>c:\warn_test\main.cpp(9) : warning C4002: too many actual parameters for macro ‘ADD’

Why isn’t this an error?

g++ (GCC) 4.2.1 20070719 [FreeBSD] gives more reasonable (in my mind) output:

main.cpp:9:18: error: macro “ADD” passed 3 arguments, but takes just 2
main.cpp: In function ‘int main(int, char**)’:
main.cpp:9: error: ‘ADD’ was not declared in this scope

Though I’m not entirely sure what either compiler thinks the third argument is.

EDIT: Added complete gcc output and version info.

Answer 1

You use ADD(1,2,), note the second ,. Remove that and it will compile just fine!

@schnaader: You are right, I read too fast. Sorry.

[edit]
Please provide more details about the compiler in question. I use: g++ (Ubuntu/Linaro 4.4.4-14ubuntu5) 4.4.5, and this is the result I get:

test.cpp:9: error: macro "ADD" passed 3 arguments, but takes just 2
test.cpp: In function ‘int main(int, char**)’:
test.cpp:9: error: ‘ADD’ was not declared in this scope

[edit2]
Sorry, again a bit too fast :-). I see you tagged it with visual studio. VS is more tolerant than g++. I suppose that — because it is easy to resolve in this case — it automatically corrects it.