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Question 
Give a oneline C expression to test whether a number is a 
power of 2?
 Question Submitted By :: Solidcube
I also faced this Question!!     Rank Answer Posted By  
 
  Re: Give a oneline C expression to test whether a number is a power of 2?
Answer
# 1		 
#include<stdio.h>
void main()
{
   int number;
    printf("|n enter a  number");
    scanf("%d",&number);
    int twopower(int);
   printf("\n the given number is ");
}
 int twopower(int num)
   {
       while((num & -num)==num)
          return(1);
        printf("|n yes power of two");
}
 
Is This Answer Correct ?    1 Yes 18 No
Sandhya
 
  Re: Give a oneline C expression to test whether a number is a power of 2?
Answer
# 2		 
#define ISPOW2(x) ( (x + (x-1) ) == (x<<1 + 1) )
 
Is This Answer Correct ?    4 Yes 17 No
Carl Menezes
 
 
 
  Re: Give a oneline C expression to test whether a number is a power of 2?
Answer
# 3		 
main()
{
int a;
scanf("%d",&a);
if((a+(a-1))==((a<<1)-1))
printf("it is powers of 2");
else
printf("not powers of 2");
}
 
Is This Answer Correct ?    4 Yes 11 No
Sathish
 
  Re: Give a oneline C expression to test whether a number is a power of 2?
Answer
# 4		 
#include<stdio.h>

main()
{
int a;
scanf("%d",&a);
if (a&1) 
printf ("POWER off 2");
printf ("NOT power of 2");
}
 
Is This Answer Correct ?    0 Yes 25 No
Mridul
 
  Re: Give a oneline C expression to test whether a number is a power of 2?
Answer
# 5		 
if (x & (x-1))  // false only if x is a power of 2
 
Is This Answer Correct ?    22 Yes 4 No
Dan
 
  Re: Give a oneline C expression to test whether a number is a power of 2?
Answer
# 6		 
#include <stdio.h>
#include <stdlib.h>
#include <math.h>

bool isPowerOf2(int number){
	if ( number > 0 )
		return (number & (number-1)) == 0;
	
	if (number == 0)
		return false;
	
	if (isPowerOf2(-number)){
		int count=0;
		while ( !(number & 1)) {
			++count;
			number >>= 1;
		}
		if (fmod(count,2))
			return true;
		else
			return false;
	}
	return false;
}

int main(void) {
	for(int i=-1027; i<1025; ++i){
		if (isPowerOf2(i) )
			printf("%d\n", i);
	}
	
	return EXIT_SUCCESS;
}
 
Is This Answer Correct ?    1 Yes 6 No
Nmk
 
  Re: Give a oneline C expression to test whether a number is a power of 2?
Answer
# 7		 
#include<stdio.h>

void main()
{
int a,i;
scanf("%d",&a);

for( i = 0; a != 0; a = a >> 1)
	if( a & 0x01 )
		i++;
if( i == 1 )
printf ("POWER off 2");
else
printf (" Not power of 2");
}
 
Is This Answer Correct ?    1 Yes 4 No
Raghavendra Donnur
 
  Re: Give a oneline C expression to test whether a number is a power of 2?
Answer
# 8		 
# include <stdio.h>

void main()
{
       int n;
       scanf("%d",&n);
       if( n & (n-1) )
           printf("Not a Power of 2");
       else
           printf("Power of 2");
}
 
Is This Answer Correct ?    20 Yes 2 No
Vadivel
 
  Re: Give a oneline C expression to test whether a number is a power of 2?
Answer
# 9		 
I think
if (x & (x-1))   wont work when number is negative.
 
Is This Answer Correct ?    3 Yes 6 No
Ashutosh
 
  Re: Give a oneline C expression to test whether a number is a power of 2?
Answer
# 10		 
if (x && !(x & (x-1)) == 0)
 
Is This Answer Correct ?    1 Yes 1 No
Phil
 
  Re: Give a oneline C expression to test whether a number is a power of 2?
Answer
# 11		 
printf("%u=%u\n", x, ((x & ~(x - 1)) == x));
 
Is This Answer Correct ?    1 Yes 1 No
Natmat
 
  Re: Give a oneline C expression to test whether a number is a power of 2?
Answer
# 12		 
x & (x - 1) == x + (x - 1)
 
Is This Answer Correct ?    0 Yes 3 No
Nikos
 
  Re: Give a oneline C expression to test whether a number is a power of 2?
Answer
# 13		 
#include<stdio.h>
main()
{
   int n,c=0,i;
   for(i=0;i<(sizeof(n)*8);i++)
      if(n&(1<<i))
        c++;
   if(c==1)
     printf("%d is powwer of 2",n);
   else
     printf("%d is not a power of 2",n);
}
 
Is This Answer Correct ?    0 Yes 1 No
Valli
 
  Re: Give a oneline C expression to test whether a number is a power of 2?
Answer
# 14		 
n%2
 
Is This Answer Correct ?    1 Yes 4 No
Ataraxic
 
  Re: Give a oneline C expression to test whether a number is a power of 2?
Answer
# 15		 
Previous post  -- It's wrong... absolutely...
 
Is This Answer Correct ?    4 Yes 0 No
Ataraxic
 
  Re: Give a oneline C expression to test whether a number is a power of 2?
Answer
# 16		 
main()
{

        int a[30];
        int i=0;
        for(i=0; i<30; i++)
                a[i]=i;
        for(i=0; i<30;i++)
        {
                if(!(a[i] & a[i-1]))
                printf("%d is power of 2\n",a[i]);
                else
                printf("%d is not a power of 2\n",a[i]);
        }



}
 
Is This Answer Correct ?    0 Yes 1 No
Xyz
 

 
 
 
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