System.out.println(040|343);

I was asked this in a Java Interview. I checked that
System.out.println(040|343); prints "345". But How? Whats the operation taking place ?

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Originally Posted by satheshshiva

I was asked this in a Java Interview. I checked that
System.out.println(040|343); prints "345". But How? Whats the operation taking place ?

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Any integer starting with a zero (0) introduces an octal representation of the number so 040 == 32 in decimal. The vertical bar (|) is the bitwise or operator, so 032 | 343 in binary is: 100000 | 101011001 == 101111001 which is 375 in decimal. I don't know where they got 345 as an answer from ...

kind regards,

Jos

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I checked that
System.out.println(040|343); prints "345"

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With small program I get "375"

Code:

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public class Bitwise {
        public static void main(String[] args) {
                System.out.println(040 | 343);
        }
}

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when you have octal number you can convert it to binary number by number. Every octal number consist of 3 binary numbers ( 2 ^ 3 = 8 ).

So how convert 40 to binary?
4 = 100 ( 1 * 2 ^ 2 + 0 * 2 ^ 1 + 0 * 2 ^ 0 )
0 = 000 ( 0 * 2 ^ 2 + 0 * 2 ^1 + 0 * 2 ^ 0)
Then you have 40 in binary 100000.

in decimal:
100000 = (1 * 2 ^ 5 + 0 * 2 ^ 4 + 0 * 2 ^ 3 + 0 * 2 ^ 2 + 0 * 2 ^ 1 + 0 * 2 ^ 0 ) = 32

and finally you have (32 | 343).

Thanks to both of you above.

Sorry for the typo.. its "375"

When one a person ever use bitwise comparison in practical applications?

EDIT: I'd be a bit chagrined if my imminent boss asked me for the result from

Code:

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System.out.println(040|343)

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at an interview lol.

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When one a person ever use bitwise comparison in practical applications?

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It's very good to use bitwise operators in many occasions.

For example if you have device with 100.000 characteristic, it's cheaper to work with bits.
100.000 characterictics (on/off) implemented with bits is like working with 100.000 / 8 = 12.500.
Program is faster, but is difficult to implement.

Bitwise operators is a connection with low level languages (asembly languague).