I have following code in .h file
#define ABC 1
#define PQR 1
#if (ABC == 1)
#define PQR 0
#endif
Is it ok to say so or do I need to say undef PQR?
What is difference between two?
Apart from this, Any link for good pre-processor tutorails is appreciated...
Thanks,
You never need to #undef. You can, but redefinition is allowed (as far as macros are concerned anyway).
Perfectly legal.Code:#define FOO 1 #define FOO 0
Quzah.
Hope is the first step on the road to disappointment.
Well if you don't use #undef, you'll probably get "macro redeclared" errors.
Like goto's, you can create a huge mess very quickly if you keep definining and undefining things, so it's use needs to be pretty exceptional.
If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
If at first you don't succeed, try writing your phone number on the exam paper.
