help me on this power of 2

[glamo]

/*following is the shortest program that finds whether the entered no. is power of two or not,but i need to add some code(logic) to it.

 

note:- program do not make use of keywords like if ,while ,for ,switch. */

 

#include<stdio.h>

void main()

{

 int n;

 char c[2][23]={"no. is not power of 2","no. is power of 2"};

 scanf("%d",&n);

 printf("%s",c[/*add code*/]);

 }

<< moderator edit: added [co[u][/u]de][/co[u][/u]de] tags >>

can anyone tell me the code i should write in printf statement so as to know that whether the number is power of 2 or not

[Dave Sinkula]

http://www.sjbaker.org/steve/software/cute_code.html

[SpS]

Nice Tricks

[rbharti]

if ( num & (num-1) == 0)
{
// it is power of 2.
}

[Dave Sinkula]

if ( num & (num-1) == 0)

Parentheses are important -- here important ones are missing.

[EsMaru]

inside the add code... put

((n & 1)+1)%2

or if u are allowed to change the char string... swap those two around and u only need

(n & 1)

[Dave Sinkula]

inside the add code... put

((n & 1)+1)%2

Without context I might then do...

if ( ((num & 1)+1)%2 )
      {
         printf("num = %d\n", num);
      }

Which is horribly wrong.

or if u are allowed to change the char string... swap those two around and u only need

(n & 1)

Again, same reply.

Please stop trying to make correct code incorrect. Or at least attempt to provide enough code to prove your point.

[EsMaru]

I'm not correcting his code or anything... my stuff is new... just copy paste what i wrote and replace /*add code*/...

as in...

/*following is the shortest program that finds whether the entered no. is power of two or not,but i need to add some code(logic) to it.

note:- program do not make use of keywords like if ,while ,for ,switch. */

#include<stdio.h>

void main()

{

int n;

char c[2][23]={"no. is not power of 2","no. is power of 2"};

scanf("%d",&n);

printf("%s",c[((n & 1)+1)%2]);

}

[Dave Sinkula]

Wow! 6 and 10 are powers of 2!
void main()!
No code tags!

[EsMaru]

oops lol was thinking multiples... sorry :rolleyes: