When should I use a bitwise operator?

Question

I read the following Stack Overflow questions, and I understand the differences between bitwise and logical.

• Difference between & and && in PHP

• Reference - What does this symbol mean in PHP?

However, none of them explains when I should use bitwise or logical.

When should I use bitwise operators rather than logical ones and vice versa?

In which situation do I need to compare bit by bit?

I am not asking about the differences, but I am asking the situation when you need to use bitwise operators.

Answer 1

Bitwise | and & and logical || and && are totally different.

Bitwise operators perform operations on the bits of two numbers and return the result. That means it's not a yes or no thing. If they're being used in conditional statements, they're often used as part of logical comparisons. For example:

if ($x & 2 == 2) {
    // The 2^1 bit is set in the number $x
}

Logical operators compare two (or more) conditions/expressions and return true or false. You use them most commonly in conditional statements, like if and while. For example:

if ($either_this || $or_this) {
    // Either expression was true
}