Detailed explanation of bit operations in php

There is a type of operators in php that are bit operations. This article mainly shares with you the detailed explanation of bit operations in php. I hope it can help you.

一:& And bitwise AND

$a&$b will set the binary $a and binary $b bits that are both 1 to 1, and the other bits to 0

For example:

7&3=>7(0111)&3(0011) It can be seen that 0111 and 0011 are both 1, only the last two 1s are, then 7(0111)&3(0011)=0011 ; 0011 is 3 in decimal, then 7&3=3

A practical use of bitwise AND is to determine parity $a&1

Principle analysis: The binary number of

1 only has the last digit is 1, other bits are all 0, and the last digit of an odd number is also 1,

For example, 11&1=>11(1011)&1(0001) = 1 is an odd number, 12&1=>12 (1100)&1=0 is an even number

This method has higher performance than $a%2==1 to determine odd and even numbers

Two:| Or bitwise or

$a|$b will set any bit in $a and $b to 1.

Example is the same as above

Three:^ Set to 1.

Example is the same as above

Four:~ Not bitwise inversion

$a~$b Set the bit that is 0 in $a to 1, and vice versa.

Example same as above

5: << Shift left (shift left)

$a<<$b;Move the bit in $a to the left$ b times (each move means "multiply by 2").

Bitwise operations are faster than multiplication and division operations, so $a*2 can be written as $a<<1

6: >>Shift right (shift right)

$a>>$b;Move the bit in $a to the right $b times (each move means "multiply by 2").

Bitwise operations are faster than multiplication and division operations, so $a/2 can be written as $a>>1

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