PHP Binary Strings vs Byte Arrays
In PHP, a binary string and a byte array are different, even though both can represent binary data.
Key Differences Between Binary Strings and Byte Arrays
| Feature | Binary String ("string") | Byte Array ("array" of bytes) |
|---|---|---|
| Type | "string" (scalar) | "array" (compound) |
| Storage | A contiguous sequence of bytes | A collection of separate integers |
| Mutability | Immutable (str_replace required) |
Mutable ($array[0] = 255;) |
| Access | $string[0] returns a string |
$array[0] returns an integer |
| Performance | More memory-efficient | Less efficient due to array overhead |
| Use Cases | File I/O, network protocols, cryptography | Byte-by-byte manipulation, calculations |
Binary String
A binary string in PHP is a "string" that contains raw binary data. Since PHP strings are binary-safe, they can hold null bytes ("\x00") and other non-printable characters.
Example: Creating a Binary String
$binaryString = "\x00\x01\x02\x03\x04"; // Binary string containing raw bytes echo bin2hex($binaryString); // Output: 0001020304
Key Characteristics
- Stored as a single contiguous block of memory.
- Supports binary-safe operations.
- Accessing "$binaryString[0]" returns a one-character string, not an integer.
Example: Accessing Binary String Characters
echo ord($binaryString[0]); // Output: 0 (ASCII value of first byte)
- "ord($binaryString[0])" converts the single-character string into an integer.
Byte Array
A byte array in PHP is an array of integers, where each element represents a single byte (0-255).
Example: Creating a Byte Array
$byteArray = [0, 1, 2, 3, 4]; print_r($byteArray);
Key Characteristics
- Each byte is stored separately as an integer.
- Directly accessible and modifiable ("$byteArray[0] = 255;").
- Less memory-efficient compared to binary strings.
Example: Accessing and Modifying Bytes
echo $byteArray[0]; // Output: 0 $byteArray[0] = 255; print_r($byteArray); // Output: [255, 1, 2, 3, 4]