V
venkatesh.k.desai5
#define PI 3.12
E
Eric Sosman
Mu.
V
venkatesh.k.desai5
I mean how much memory it will take?
Eric said:
T
Tak-Shing Chan
3.12 is of type double, therefore sizeof PI is the same as
sizeof(double).
Tak-Shing
F
Frederick Gotham
(e-mail address removed) posted:
It's about an inch and a half wide on my screen.
If you need it smaller, try changing screen resolution -- should shave off a
few clock cycles.
It's about an inch and a half wide on my screen.
If you need it smaller, try changing screen resolution -- should shave off a
few clock cycles.
V
venkatesh.k.desai5
But how is it? compiler will allocate memory.
Tak-Shing Chan said:
V
Vlad Dogaru
Mine shows 3.14, but maybe your's is late. Are the batteries dead?
R
Richard Heathfield
(e-mail address removed) said:
Why?
Why?
C
Christopher Benson-Manica
Vlad Dogaru said:Mine shows 3.14, but maybe your's is late. Are the batteries dead?
It's 3.00 on mine, but I'm running on a King Solomon model, so
apparently it's a QOI issue.
V
venkatesh.k.desai5
Richard said:
Coz macro's are processed in CPP.
D
Default User
Please read the information below.
Brian
J
J. J. Farrell
You are asking questions which don't make much sense, and making
statements which don't seem to be related to the questions or the
discussion. This suggests that you have some fundamental
misunderstanding of something. If you give a more complete description
of what is puzzling you, perhaps with some example code, we may be
better able to help you understand the issue.
K
Keith Thompson
[email protected] said:
Please put the question in the body of your article. Not all newsreaders
show the subject along with the body of the message.
The question was "what is size of this macro?". As you say later,
you're asking how much memory is allocated.
The answer is none. Macros don't allocate memory; they perform
textual substitution on your source code.
By itself, the macro definition
#define PI 3.12
will simply disappear from your program if you don't use it.
If you do use it, each occurrence of PI in your source will simply be
replaced with 3.12. What this does depends on how you use it.
The literal 3.12 is of type double, if that's what you were wondering about.
E
Eric Sosman
"None." Or "sizeof(double)." Or "too much." All
these answers, and more, are defensible. The question
is not well-formed, and suggests that you may not quite
understand what macros are or how they operate in your
program source. I recommend that you return to your C
textbook and re-read the section on macros, and perhaps
write a few short programs with and without using macros
(other than those you simply cannot avoid if you want to
use the library functions). If things remain unclear,
come back and ask more questions -- but the question you
are asking now indicates there's a basic flaw somewhere
in your understanding.
R
Richard Heathfield
(e-mail address removed) said:
So what makes you think the compiler will allocate memory for PI? It won't
even /see/ PI, because - as you say - macros are processed by the
preprocessor.
So what makes you think the compiler will allocate memory for PI? It won't
even /see/ PI, because - as you say - macros are processed by the
preprocessor.
J
Joe Wright
The compiler doesn't involve itself in #define thingies. The compiler
never sees PI. The preprocessor has already replaced PI with 3.12 and,
correct or not, this is what the compiler eventually sees.
K
Keith Thompson
Joe Wright said:
That's assuming that you don't consider the preprocessor to be part of
the "compiler".
M
my.correo.basura
Eric said:
Sometimes I wonder: Would I be happier if I didn't understand comments
like this one? Then again, the answer is Mu.
R
Richard Bos
Christopher Benson-Manica said:
It certainly is: the King Solomon Specification only specifies a single
digit of precision, so your model is giving you a precision that isn't
actually justified by the docs.
Richard
A
Ancient_Hacker
How much memory will WHAT take, when, and on which compiler, what
platform?
Choices for "what" and "when":
(1) The line of text, in the source file.
(2) The macro, in the compiler, at compile time.
(3) The macro, at link time.
(3) The macro, at run time
You may need to read up on macros, and exactly how they get processed.