power of two...

[Shraddha]

How to find the power of two (2 rais to n) in a single step???

 

[Tim Prince]

How to find the power of two (2 rais to n) in a single step???

Start with Google, it will help you with spelling.

 

[Joachim Schmitz]

How to find the power of two (2 rais to n) in a single step???

With the shift operator (for integer values) or with pow() (for double
values)

Bye, Jojo

 

[Richard Heathfield]

Shraddha said:

How to find the power of two (2 rais to n) in a single step???

double single_step = pow(2, n);

 

[Joachim Schmitz]

Shraddha said:


double single_step = pow(2, n);

Passing integer values to a function expecting double without a prototype in
sight?

Bye, Jojo

 

[Sharath]

How to find the power of two (2 rais to n) in a single step???

I think you mean to find whether the given number is a power of two in
a single step,
which is a frequently asked question (especially in tech interviews of
Indian companies).
Read this: http://prokutfaq.byethost15.com/PowerOfTwo

 

[Ben Pfaff]

How to find the power of two (2 rais to n) in a single step???

As an unsigned long int: 1UL << n.
As a double: pow(2.0, n).

 

[Richard Heathfield]

Joachim Schmitz said:

Passing integer values to a function expecting double without a
prototype in sight?

The prototype is in <math.h>

Note also the absence of a function in which the code needs to be
enclosed.

 

[Fred Kleinschmidt]

How to find the power of two (2 rais to n) in a single step???

Look at the << operator

 

[Boudewijn Dijkstra]

Op Mon, 11 Jun 2007 16:20:51 +0200 schreef Richard Heathfield

Joachim Schmitz said:

The prototype is in <math.h>

Note also the absence of a function in which the code needs to be
enclosed.

Note also the absence of a compilation unit (or file) in which the
function needs to be enclosed.

 

[user923005]

How to find the power of two (2 rais to n) in a single step???

I am guessing that what you are really asking is how to find out if an
integer number is an integral power of 2.
A simple way to do that is to do a bitcount and see if it is 1.

Maybe something like this:

int bitcount (unsigned long n)
{

n = (n & 0x55555555) + ((n >> 1) & 0x55555555);
n = (n & 0x33333333) + ((n >> 2) & 0x33333333);
n = (n + (n >> 4)) & 0x0f0f0f0f;
n += n >> 8;
n += n >> 16;
return (n & 0xff);
}

then...

if (bitcount(n) == 1) puts("It's a power of 2");
else puts("It is not a power of 2");

 

[Ben Pfaff]

I am guessing that what you are really asking is how to find out if an
integer number is an integral power of 2.

x != 0 && !(x & (x - 1))