Login | Register   
LinkedIn
Google+
Twitter
RSS Feed
Download our iPhone app
TODAY'S HEADLINES  |   ARTICLE ARCHIVE  |   FORUMS  |   TIP BANK
Browse DevX
Sign up for e-mail newsletters from DevX


Tip of the Day
Home » Tip Bank » C++
Language: C++
Expertise: Beginner
Apr 24, 2000

Undoing a Macro

If you happen to define an object or a function or a constant whose name collides with a macro located elsewhere in a third-party header file, as in:

 
  // file defs.h 
  //...many declaration
  #define PI 3.14

  // your program:
  #include "defs.h"
  const double PI = 3.14159265358; // error, 'PI' redefined

you can use the #undef preprocessor directive to cancel a previously-defined macro:

 
  #include "defs.h"
  #undef PI  // from now on, ignore the PI macro
  const double PI = 3.14159265358979 // OK
Danny Kalev
 
Comment and Contribute

 

 

 

 

 


(Maximum characters: 1200). You have 1200 characters left.

 

 

Sitemap
Thanks for your registration, follow us on our social networks to keep up-to-date