Why is the answer of the following line is 1?

Question

int x = 1 - ( - 1 == ~0);

Answer 1

Edited answer, Thanks to my friend CarrieForle for correcting me 😊

Manthan Gohel results will *not* be 1, it'll be 0.

~ complements bits of number. 0's become 1 and 1's become 0. well 0 and 1 represent bits(states) not decimal integer numbers.

in general a signed integer is represented as sequence of 32 bits (4bytes).

when you use bitwise operators you are actually working on its bits.

just assume that int is being represented with 8 bits then 0 will be represented as 00000000
in binary. on applying ~ bitwise not you get 11111111 that represents -1.

-1 == -1 is true when you typecast boolean `true` to integer it becomes 1.
(*Just for your info that `false` becomes 0.)

So expression becomes
int x=1-1;
So answer is 0.

●Try to search on net about :
*Bitwise operators
*Implicit and explicit typecasting/ type conversion

Answer 2

CarrieForle 🤯
Thanks friend 😊🙏

I was wrong , smart of you 🤓.

Well integers are represented with multiple bits in memory.
If you represent int with suppose 8 bits(generally 32 bit but just assume ) 0 will be as 00000000 in memory and on complementing it'll be 11111111 representing -1.

and yes finally x will be 0.

Thanks a lot. 😁😁😁😁😁

Answer 3

Take a look: https://www.sololearn.com/learn/4076/?ref=app

Answer 4

🇮🇳Omkar🕉 //Busy , Exams. I did a test but it shows that the output is 0.
https://code.sololearn.com/c1EP34NidM0Y/?ref=app

Answer 5

Manthan Gohel yeah correct friend. When MSB (most significant bit) is 1 it's a negative number.

Just to get a little clear idea assuming signed int is being represented with 4 bits only. 4 bits can represent upto 2^4 = 16 decimal numbers.

Then half (8) combinations of 4 bits will represent positive and half(8) will represent negative numbers.

Positive no : 0000, 0001, 0010, 0011, 0100 , 0101, 0110, 0111

Negative no :1000, 1001, 1010, 1011, 1100, 1101, 1110, 1111

observe how numbers with msb 1 are negative.

Answer 6

i think that code help for you:

here the difference between these operations (-, !, ~, !!, ~~) and the representation of signed numbers in the "int" type are presented.

https://code.sololearn.com/ceccnWD8vvLQ/?ref=app

Answer 7

But,
How can 11111111 become 0?
Because it is signed integer?
I think first 1 represents - sign in binary signed digit, correct me if I am wrong please.

Answer 8

🇮🇳Omkar🕉 //Busy , Exams. Yeah, I learned it in my diploma college 1month ago, i am just getting started, I am doing diploma in CE.

Answer 9

Thanks Bro, I was a bit confused

Answer 10

Michail Getmanskiy Thanks man, appreciate that😊