if it's gonna be a function the call is like:Code:#define max(x,y) (x)>(y)?(x):(y) ......... ............. ......... int a=5,b=3; int k=max(a++,++b); cout<<k; ...............
but when its, macro how the call ll be and how the proccesing will be?Code:max(5,4)
a detailed explanation pls
Perform the macro expansion yourself then reason about the resulting code:
Consequently, it would be better to use an inline function template instead of a macro.Code:int a=5,b=3; int k=(a++)>(++b)?(a++):(++b); cout<<k;
Look up a C++ Reference and learn How To Ask Questions The Smart WayOriginally Posted by Bjarne Stroustrup (2000-10-14)
yes i know.but the answer is different from what we have in function...
The called number is not 5,4 basically
take for example:
i thought the answer would be: 11,6,10Code:#define MAN(x,y) (x)>(y)?(x):(y) ............. int i=10,j=5,k=0; k= MAN(i++,++j); printf("%d %d %d",i,j,k);
but the answer is 12,6,11
how is it
. . . think about it for one moment, here. laserlight has suggested you expand it out yourself, which s/he has done kindly for you.
How many times is a going to be incremented? How about b?
-- strange
There is no Darkness in Eternity
Only Light too dim for us to see
If you know, then there should be no "but"
There is a sequence point at the '?'. So, the post-increment would have been effective by the time control reaches the second or third operands of the ternary operator, whereas with a function call the first argument would have the original value of a.
What do you mean by "called number"? There is no function call.
Look up a C++ Reference and learn How To Ask Questions The Smart Way
yeahthanks
That's exactly why macros are evil and should be avoided whenever possible.
"I am probably the laziest programmer on the planet, a fact with which anyone who has ever seen my code will agree." - esbo, 11/15/2008
"the internet is a scary place to be thats why i dont use it much." - billet, 03/17/2010
What laserlight and cpjust are pointing out:
Post and pre incrementing on the same line bring out demons in your code, especially if macros are used in tandem with increment operators. Your macro will just expand this out. Troubleshooting these are a pain as well. Caution is very much needed when you define those. I have done something similar to the following:
Code:/* Some universal defines to aid in swapping out two keys of int types */ typedef int Item; /*can easily be modified as necessary */ #define key(A) (A) #define less(A, B) (key(A) < key(B)) #define exch(A, B) {Item t = A; A = B; B = t;} /* more defines built from above definitions */ #define compexch(A, B) if (less(B, A)) exch(A, B)
