PHP

PHP

⚙️ Bitwise Operators in PHP

Bitwise Operators in PHP perform evaluations and manipulations directly at the bit level (0s and 1s). Integers are converted into their binary representations, processed bit-by-bit using Boolean logic, and evaluated back to integer values.

  • Key Characteristics: Bitwise operators process integer values by evaluating corresponding binary positions. Except for Bitwise NOT (~), which is a unary operator, all bitwise operations take two operands.

🛠️ How Bitwise Operators Work

Consider two sample integer values and their 8-bit binary equivalents:

$a = 22;  ➔  00010110
$b = 3;   ➔  00000011

🔍 PHP Bitwise Operators and Syntax

1️⃣ Bitwise AND (&)
Returns 1 only if both evaluated bits are 1; otherwise, returns 0.

PHP
$a = 22; // 00010110
$b = 3;  // 00000011

$result = $a & $b; 
// 00010110 & 00000011 = 00000010 (Decimal: 2)

echo $result; // Outputs: 2

2️⃣ Bitwise OR (|)
Returns 1 if at least one of the corresponding bits is 1.

PHP
$a = 22; // 00010110
$b = 3;  // 00000011

$result = $a | $b; 
// 00010110 | 00000011 = 00010111 (Decimal: 23)

echo $result; // Outputs: 23

3️⃣ Bitwise XOR (^)
Returns 1 if the compared bits are different, and 0 if they are identical.

PHP
$a = 22; // 00010110
$b = 3;  // 00000011

$result = $a ^ $b; 
// 00010110 ^ 00000011 = 00010101 (Decimal: 21)

echo $result; // Outputs: 21

4️⃣ Bitwise NOT (~)
Inverts all bits (1 becomes 0, and 0 becomes 1).

PHP
$a = 22; // 00010110

$result = ~$a; 
// Inverts bits: 11101001

echo $result; // Note: Outputs two's complement signed integer (-23)

5️⃣ Left Shift (<<)
Shifts bits to the left by the specified number of positions and pads 0s to the right. Equivalent to multiplying by powers of 2 ($a \times 2^n$).

PHP
$a = 22; // 00010110

$result = $a << 3; 
// 00010110 << 3 = 10110000 (Decimal: 176)

echo $result; // Outputs: 176

6️⃣ Right Shift (>>)
Shifts bits to the right by the specified number of positions. Equivalent to integer division by powers of 2 ($\lfloor a / 2^n \rfloor$).

PHP
$a = 22; // 00010110

$result = $a >> 3; 
// 00010110 >> 3 = 00000010 (Decimal: 2)

echo $result; // Outputs: 2

💡 Common Use Cases

Bitwise operators are applied in specialized low-level contexts:

  • Permission Flags: Authorization systems store multiple boolean settings into a single integer mask.
  • Performance Optimization: High-frequency mathematical operations like bit masking and power-of-two arithmetic.
  • Encryption & Compression: Data encoding, checksum hashing algorithms, and bit masking.

📊 Bitwise Operators Reference Table

Operator Name Example Description
& Bitwise AND $a & $b Bits that are 1 in both $a and $b are set to 1.
| Bitwise OR $a | $b Bits that are 1 in either $a or $b are set to 1.
^ Bitwise XOR $a ^ $b Bits that are 1 in either $a or $b, but not both, are set to 1.
~ Bitwise NOT ~$a Inverts all bits (0 to 1, 1 to 0).
<< Shift Left $a << $b Shifts bits of $a to the left by $b steps.
>> Shift Right $a >> $b Shifts bits of $a to the right by $b steps.

  • 📝 Short Summary

  • Bitwise operators process numbers at their individual binary bit levels.
  • Shift operators (<<, >>) allow fast multiplication and division by powers of 2.
  • Bitwise NOT (~) results depend on signed integer representation in 64-bit PHP architecture.
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