CareerCup

for unsigned integer nummbers:
bool isPow2(int n)
{
return !(n & (n-1)) && n;
}

if number of bits set is 1 then it is a power of two

for unsigned integer numbers:
bool isPow2(int n)
{
return !(n & (n-1)) && n;
}

return num&(num-1)==0

return ((pow(2,log2(n))-pow(2,floor(log2(n))))==0)

bool isPow2(unsigned int n){
if(n==0)
return false;
return (n&(n-1))==0;
}

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

@Jay: Thats interesting point. I was wondering if Negative numbers can be powers of positive number!

bool ispowerof2(int x)
{
int p = x & -x;
return p == x || p == -x;
}

powers of a +ve number 2 will always be +ve

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
bool val ( int n);
int main ()
{
if(val(1024) == true)
cout << "yes";
else
cout <<"no";

}

bool val(int n)
{

if( n <= 1)
return false;

while(n>1)
{
if(n%2 != 0)
return false;
else
n = n / 2;
}

return true;
}

static void Main(string[] args)
{
int number = enter any no;
int quotient = 0;
int mod = 0;
while(number >= 2)
{
mod = number % 2;
quotient = number / 2;

if (mod == 0 && number >= 2)
{
number = quotient; ;
continue;
}
else break;
}
if (mod == 0)
{
Console.WriteLine("number power of 2");
}
else
{
Console.WriteLine("number not power of 2");
}
Console.ReadLine();
}

What about negative number? such as -4. -4 is power of 2 too.