Predict the output and use of i&1 in that code

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C#

for(int i=0;i<10;++i){
                System.out.print(i&1);
            }

Posted 23-Jun-15 22:53pm

shivakumar rudroju

Updated 23-Jun-15 23:15pm

v2

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phil.o 24-Jun-15 5:14am

What is the question?

shivakumar rudroju 24-Jun-15 5:16am

what does i&1 do ?

phil.o 24-Jun-15 5:28am

It performs a logical AND between the variable i and the number one.
Logical AND.

3 solutions

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CPallini · Answer 1 · 2015-06-23T23:12:00

Solution 1

OK, I compiled a ran a fixed version of your program for you:

Java

public class Bin
{
  public static void main( String args[])
  {
    for(int i=0;i<10;++i)
    {
      System.out.print(i&1);
    }
  }
}

output:

0101010101

Is it a surprise?

Posted 23-Jun-15 23:12pm

CPallini

OriginalGriff · Answer 2 · 2015-06-23T23:28:00

The & operator in Java is a bitwise AND - which returns zero where any bit in either side of the operator is zero, and one only where the bit in the same position on both sides is one.

So i&1 will return the least significant bit of the number: because you specified the constant 1 - which has only a single bit set, in the least significant position it will ignore all the other bits in the integer, and return a one or zero based solely on the content of the least significant bit.

And since you increase i by one each time you go round the loop, the value of that least significant bit will change from 0 to 1 each time round. You start with zero, and the last time round the loop is with i equal to nine, so you will end with one:

0101010101

Member 11789906 · Answer 3 · 2015-06-24T13:47:00

Solution 3

C++

0101010101

Posted 24-Jun-15 13:47pm

Member 11789906