Any build macro to compute the powers of int number?

[PengYu.UT]

Hi All,

For example, I want to declare an array

double array[VERY_VERY_VERY_LONG_NAME * VERY_VERY_VERY_LONG_NAME *
VERY_VERY_VERY_LONG_NAME * VERY_VERY_VERY_LONG_NAME];

Of cause, I can define an macro for the 4th power of
VERY_VERY_VERY_LONG_NAME. But I want to know whether there is any build
in macro to compute the powers. Thanks!

Best wishes,
Peng

 

[Ben Pfaff]

double array[VERY_VERY_VERY_LONG_NAME * VERY_VERY_VERY_LONG_NAME *
VERY_VERY_VERY_LONG_NAME * VERY_VERY_VERY_LONG_NAME];

Of cause, I can define an macro for the 4th power of
VERY_VERY_VERY_LONG_NAME. But I want to know whether there is any build
in macro to compute the powers. Thanks!

No.

 

[Chris Croughton]

For example, I want to declare an array

double array[VERY_VERY_VERY_LONG_NAME * VERY_VERY_VERY_LONG_NAME *
VERY_VERY_VERY_LONG_NAME * VERY_VERY_VERY_LONG_NAME];

Of cause, I can define an macro for the 4th power of
VERY_VERY_VERY_LONG_NAME. But I want to know whether there is any build
in macro to compute the powers. Thanks!

No. That was an easy one <g>. Your best bet is as you say to define a
macro to do it:

#define POW4(a) ((a)*(a)*(a)*(a))

(don't forget the parentheses otherwise POW4(1+2) will have really weird
effects!)

But if you need POW(x,y) where both are macros, I'm afraid you're stuck.
The C preprocessor isn't that pow-erful (sorry, couldn't resist the
pun!)...

Chris C

 

[Walter Roberson]

:Of cause, I can define an macro for the 4th power of
:VERY_VERY_VERY_LONG_NAME. But I want to know whether there is any build
:in macro to compute the powers. Thanks!

pow() is the closest, but it is a function not a macro, and it takes
and returns double, not int. Not suitable for a constant subscript
in other words.

You could do the usual -- define a macro for x*x and then
x**4 is square(square(x))

 

[Tor Rustad]

You could do the usual -- define a macro for x*x and then
x**4 is square(square(x))

#define POW4(x) ((x)*(x)*(x)*(x))

is shorter.