Displaying a decimal number into its equivalent Binary number

Question

I tried the following code for displaying a number's binary equivalent but i am getting an error and i am not getting the reason behind the error:

using System;

class NumToBin{
     static void main(){
        int num=7;
        for(int i=0;i<=32;i++){
            if(num &(1<<i)==1)// getting an error on this line
                Console.WriteLine("1");
            else
                Console.WriteLine("0");
        }
        Console.ReadKey(true);
    }
}

I got the following error for the above code and i dont know the reason behind this error?

Operator '&' cannot be applied to operands of type 'int' and 'bool' (CS0019)

Also, for reference (even though this really isn't what your question is about): http://stackoverflow.com/questions/923771/quickest-way-to-convert-a-base-10-number-to-any-base-in-net — jeffrey_t_b, Oct 29 '12 at 17:41
@L.B: Your comment deserves to be a full-fledged answer. Anytime you can reduce code by 90% or so is a beautiful thing! — Michael Sorens, Oct 30 '12 at 15:17

Zbigniew · Answer 1 · 2012-10-29T17:41:25.423

5

Error is a result of operator order of precedence, to fix it you simply need to add parentheses, change:

if(num &(1<<i)==1)

to

if((num & (1<<i)) == 1)

edited Oct 29 '12 at 17:41

answered Oct 29 '12 at 17:36

Zbigniew

27,184
6
59
66

Richard Schneider · Accepted Answer · 2012-10-29T18:22:39.623

2

Operator precedence error, try if ((num & (1<<i)) == 1)

There are only 32 bits in an int. Change for loop predicate to i < 32, instead of i<=32.

or:

for(int i=0; i < 32; i++)
    Console.WriteLine((num & (1<<i)) == 0 ? "0" : "1");

UPDATED

for(int i=31; 0 <= i; --i)
    Console.WriteLine(((num >> i) & 1) == 0 ? "0" : "1");

edited Oct 29 '12 at 18:22

answered Oct 29 '12 at 17:42

Richard Schneider

34,944
9
57
73

With your logic i am getting 11100000000000000000000000000000 for 7. Can i anyhow reverse it to get 00000000000000000000000000000111 which is more meaningful for binary numbers? – Afaq Oct 29 '12 at 17:56
@Raptor - Reverse your for loop. Count from 32 down to 0. – Dave Zych Oct 29 '12 at 17:58
@Richard Schneider- The updated code is still giving the same output. – Afaq Oct 29 '12 at 18:11
@Raptor, sorry its getting late in bangkok and my mind is lazy! – Richard Schneider Oct 29 '12 at 18:15
@RichardSchneider, Sorry to bother you again, but now its going in an infinite loop. You wrote i++ instead of i-- – Afaq Oct 29 '12 at 18:20

Displaying a decimal number into its equivalent Binary number

2 Answers2