What is the C++ function to raise a number to a power?

Question

How do I raise a number to a power?

2^1

2^2

2^3

etc...

Answer 1

pow() in the cmath library. More info here.

Answer 2

pow

Answer 3

Use the pow(x,y) function: See Here

Just include math.h and you're all set.

Answer 4

It's pow or powf in <math.h>

There is no special infix operator like in Visual Basic or Python

Answer 5

pow(2.0,1.0)
pow(2.0,2.0)
pow(2.0,3.0)

Your original question title is misleading. To just square, use 2*2.

Answer 6

You should be able to use normal C methods in math.

#include <cmath>

pow(2,3)

if you're on a unix-like system, man cmath

Is that what you're asking?

Sujal

Answer 7

While pow( base, exp ) is a great suggestion, be aware that it typically works in floating-point.

This may or may not be what you want: on some systems a simple loop multiplying on an accumulator will be faster for integer types.

And for square specifically, you might as well just multiply the numbers together yourself, floating-point or integer; it's not really a decrease in readability (IMHO) and you avoid the performance overhead of a function call.

Answer 8

Some lawyer crap from me again. I've often fallen in this pitfall myself, so i'm going to warn you about it. std::pow in the <cmath> header has these overloads:

pow(float, float);
pow(float, int);
pow(double, double); // taken over from C
pow(double, int);
pow(long double, long double);
pow(long double, int);

Now you can't just do

pow(2, N)

with N being an int, because it doesn't know which of float, double or long double version it should take, and you would get an ambiguity error. All three would need a conversion from int to floating point, and all three are equally costly!

Therefor, be sure to have the first argument typed so it matches one of those three perfectly. I usually use double

pow(2.0, N)

Answer 9

I think, if you use the way which you know, it will be better.. here it is..

#include <math.h>


struct float_t
{

    float value;

    float_t(float v)
    {
     value = v;
    }
    operator float()
    {
     return value;
    }
    float operator ^(float c)
    {
     return powf(value, c);
    }
};

int _tmain(int argc, _TCHAR* argv[])
{

    float_t num(4);
    printf("%f", num ^ 3);
}