MSVC++ how to ouput something to the "output"-window during compilation

Question

sometimes i see that certain projects write something to the output during compilation.

how can that be achieved in MSVC++

thanks!

score 13 · Accepted Answer · answered Jul 24 '09 at 11:50

13

use #pragma message e.g.

#define MESSAGE(t) message(__FILE__ "(" STRINGXXX(__LINE__) ") : " t)
#define STRINGXXX(x) STRINGYYY(x)
#define STRINGYYY(x) #x

then if you put

#pragma MESSAGE("TODO: testing")

it will appear as a clickable message just like the normal compiler messages

answered Jul 24 '09 at 11:50

Steve Gilham

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Why STRINGXXX and STRINGYYY instead of just one macro? – rpg Jul 24 '09 at 12:54
__LINE__ is a number and it needs to be transformed into a string. You use another macro in order to avoid having the string "__LINE__" all over the place. – Cristian Adam Jul 24 '09 at 14:00
1

You can also use _CRT_STRINGIZE defined in crtdefs.h so you only need to define the macro MESSAGE – Stephen Nutt Aug 12 '09 at 11:29

score 6 · Answer 2 · answered Jul 24 '09 at 11:49

6

You want to include something like this in your source code:

#pragma message("Hello World")

answered Jul 24 '09 at 11:49

Timo Geusch

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score 2 · Answer 3 · answered Jul 24 '09 at 11:51

2

You can use #pragma message in one of your source files to output a string when that file is preprocessed.

Also, when a custom, pre- or post- build step is executed, the "description" field is echoed to standard output.

answered Jul 24 '09 at 11:51

Nick Meyer

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score 1 · Answer 4 · answered Jul 24 '09 at 12:02

As Timo Geusch said: the #pragma message directive is used for that.

As an exotic side effect of template metaprogramming, it's also possible to use the compiler as a calculator :)

template<int i> struct Message;

template<int i> struct Fac {
   static const int v = i * Fac< i-1 >::v; 
};

template<> struct Fac<1> { static const int v = 1; };

Message< Fac<10>::v > m;

will result in the output message

Line 10: error: aggregate 'Message<3628800> m' has incomplete type and cannot be defined

MSVC++ how to ouput something to the "output"-window during compilation

4 Answers4

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