Exponential Operator in C++

+6 A:

There are pow and exp functions in math library.

ArunSaha 2010-09-23 03:26:25

I just learned this after much "Google-ing". :)

James Hayek 2010-09-23 20:50:03

+20 A:

You don't write a function for this (unless you're mad, of course). There's a perfectly good pow function defined in cmath.

Aside: if you try to use ^ as a power operator, you'll be in for a nasty surprise :-)

paxdiablo 2010-09-23 03:27:35

+1: Both of us pointed to the same link :)

ArunSaha 2010-09-23 03:29:28

the lovely ^ trap ;)

Marlon 2010-09-23 03:49:13

It only works for `1^0`.

dan04 2010-09-23 04:57:13

Ha! I just found out that ^ is an OR operator ;)

James Hayek 2010-09-23 20:51:20

Its *NOT* OR, its XOR :) See: http://en.wikipedia.org/wiki/Bitwise_operation#XOR

ArunSaha 2010-09-23 20:59:21

+7 A:

Most C operations readily ~~intended to~~ mapped to a single processor instruction when C was invented. At the time, exponentiation was not a machine instruction, thus the library routine.

msw 2010-09-23 03:27:52

"Intended" may be too strong. C *did* map fairly directly onto the instruction sets of common architectures of the era, but I've never read of K *or* R saying "we can't have that feature, it's not something the machine does...".

dmckee 2010-09-23 03:37:07

In fact, float-to-int casts and back are implicit, i.e. don't require an operation, but they were far more expensive than a single processor instruction.

MSalters 2010-09-23 07:49:46

A:

What platform and which compiler are you using? My guess is TurboC. Mostly cmath file has most of the mathematical functions covered in other compilers.

Manoj R 2010-09-23 07:07:57

XCode at home, Visual Studio at school.

James Hayek 2010-09-23 20:50:46

ansaurus

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Exponential Operator in C++

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