The meaning of the symbol ~ on an array when that array is not a class

Question

I'm reading a C ++ code, the code has a line like this:

for(;;) 
{
    if(~theArray[i] & anotherCondition)
    {
        DoSomeThing();
    }
}

For some values i code goes back to the beginning of the loop, what exactly does this expression ~ on array, do?

Can anybody help?

It doesn't do anything on an array. `theArray[i]` is not an array, it's an array element. — Barmar, Feb 01 '22 at 08:32
This performs a bitwise NOT of the array element, then a bitwise AND of that with `anotherCondition`. — Barmar, Feb 01 '22 at 08:33
It does the same thing for array elements that it does for any other value. — Barmar, Feb 01 '22 at 08:34
`~` is a bitwise operator. In particular, `~` is a **not** operator, which negates the value. — Shafa95, Feb 01 '22 at 08:35
`if(~theArray[i] & anotherCondition)` is equivalent to `int arrayElementValue = theArray[i]; if(~arrayElementValue & anotherCondition)` (assuming that `theArray` is an array of `int` elements). — Some programmer dude, Feb 01 '22 at 08:36
if you have some code that "goes back to the beginning of the loop" then it isnt the code you posted. Perhaps you simplified too much. The code you posted is an infinite loop — 463035818_is_not_an_ai, Feb 01 '22 at 08:38

score 0 · Answer 1 · answered Feb 01 '22 at 08:39

0

Sign '~' means negation, NOT. I guess if the array element is for example 00101001 in binary, then it will be changed to 11010110 for the operations inside 'if'.

answered Feb 01 '22 at 08:39

WojciechCode

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A better term might be *bitwise complement* not negation. – Some programmer dude Feb 01 '22 at 08:39

score 0 · Accepted Answer · edited Feb 01 '22 at 08:47

0

~ operator indicates bitwise complement.

Bitwise complement operator is an unary operator (works on only one operand). It changes 1 to 0 and 0 to 1.

For example:

35 = 00100011 (In Binary)

complement of 35 is

~ 00100011 = 11011100 which is equal to 220 (In decimal)

Please check below resources to learn more about it

Bitwise Operators

Bitwise Complement Operator

edited Feb 01 '22 at 08:47

463035818_is_not_an_ai

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answered Feb 01 '22 at 08:40

Md. Faisal Habib

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The meaning of the symbol ~ on an array when that array is not a class

2 Answers2