PHP Bitwise Operators

While we commonly use PHP for high-level logic and data manipulation, sometimes venturing into the realm of low-level operations can be useful. This is where bitwise operators come in. These operators allow us to perform operations directly on individual bits within an integer, offering unique functionalities and unexpected efficiencies.

This article aims to explain PHP's bitwise operators, providing a clear understanding of their purpose and usage.

What are Bits and Why Should We Care?

Computers store information in binary form, using sequences of 0s and 1s called bits. Each bit represents a single value, and eight bits together form a byte. Understanding bits becomes crucial when dealing with memory manipulation, low-level programming, and optimizing code performance.

Exploring the Bitwise Operators in PHP:

PHP offers a variety of bitwise operators, each serving a specific purpose:

Bitwise AND (&): Performs an AND operation on each corresponding bit of two operands. The result is 1 only if both bits are 1, otherwise it's 0.

$a = 6 (0110 in binary);
$b = 5 (0101 in binary);

$result = $a & $b; // $result will be 4 (0100 in binary)

Bitwise OR (|): Performs an OR operation on each corresponding bit. The result is 1 if either bit is 1, or both are 1.

$a = 6 (0110 in binary);
$b = 5 (0101 in binary);

$result = $a | $b; // $result will be 7 (0111 in binary)

Bitwise XOR (^): Performs an XOR operation on each corresponding bit. The result is 1 if only one of the bits is 1, otherwise it's 0.

$a = 6 (0110 in binary);
$b = 5 (0101 in binary);

$result = $a ^ $b; // $result will be 3 (0011 in binary)

Bitwise NOT (~): Inverts the bits of an operand.

$a = 6 (0110 in binary);

$result = ~$a; // $result will be -7 (1001 in binary) (two's complement)

Left Shift (<<): Shifts the bits of the operand to the left by the specified number of positions.

$a = 6 (0110 in binary);

$result = $a << 1; // $result will be 12 (1100 in binary)

Right Shift (>>): Shifts the bits of the operand to the right by the specified number of positions. Filling bits with 0s by default (unsigned right shift) and replicating the sign bit (signed right shift).

$a = 6 (0110 in binary);

$result = $a >> 1; // $result will be 3 (0011 in binary) (unsigned right shift)

Applications of Bitwise Operators:

Bit manipulation: Enabling and disabling flags within an integer.
Memory Optimization: Compactly storing boolean values or multiple flags within a single integer.
Efficient comparisons: Checking if a number is even or odd using bitwise AND with 1.
Cryptography: Implementing simple encryption and decryption algorithms.

Important Considerations:

Bitwise operators work on integers, not strings or other data types.
Understanding binary representation is crucial for efficient usage.
Overuse can make code complex and harder to maintain. Use them judiciously when other solutions are less efficient.

PHP Bitwise Operators
PHP | Bitwise Operators
A Guide to PHP Bitwise Operators