How to print the #define statement?

Question

How can I get cerr to print 5 < 6 as opposed to statement_? I have access to Boost and Qt.

using namespace std;

#define some_func( statement_ )               \
  if( ! statement_ )                          \
  {                                           \
    throw runtime_error( "statement_" );      \
  }                                           \

int main()
{
  try
  {
    some_func( 5 < 6 );
  }
  catch(std::exception& e)
  {
    cerr << e.what();
  }
}

Community · Accepted Answer · 2017-05-23 11:52:30Z

4

You need to use the stringize operator:

throw runtime_error(# statement_);

If statement_ may be a macro, you'll want to use the double stringize trick.

edited May 23, 2017 at 11:52

CommunityBot

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answered Dec 21, 2010 at 1:06

James McNellis

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Comments

Loki Astari · Accepted Answer · 2010-12-21 01:15:21Z

1

Oh, I found this.

and here's the final working code =):

#include <stdexcept>
#include <iostream>

#define some_func( statement_ )              \
  if( ! statement_ )                         \
  {                                          \
    throw std::runtime_error( #statement_ ); \
/* Note: #, no quotes!       ^^^^^^^^^^  */  \
  }                                          \

int main(int argc, char** argv)
{
  try
  {
    some_func( 5 < 6 );
  }
  catch(std::exception& e)
  {
    std::cerr << e.what();
  }
}

edited Dec 21, 2010 at 1:15

Loki Astari

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answered Dec 21, 2010 at 1:06

sivabudh

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