Single Quotes vs. Double Quotes in PHP Strings: When Should I Use Which?

Single-Quotes vs. Double-Quotes in PHP Strings

In PHP, there are four methods of specifying strings:

1. Single-Quoted Strings

Single quotes render strings literally, preserving escape sequences (except for single quotes with backslash and double backslashes) and ignoring variables.

2. Double-Quoted Strings

Double quotes interpret escape sequences and evaluate variables. Variables can be isolated within curly braces (e.g., "The {$type}s are").

3. Heredoc Syntax

Starts with <<< followed by an identifier,newline, and terminates with the identifier enclosed in double quotes. Interprets escape sequences and variables, like double-quoted strings.

4. Nowdoc Syntax

Starts with <<< followed by an identifier enclosed in single quotes, newline, and terminates with the identifier. Does not interpret any escape sequences or variables.

Note: Single quotes within single quotes and double quotes within double quotes require escaping.

Speed Comparison:

Contrary to popular belief, there is no performance difference between using single and double quotes for strings in PHP. The parsing process occurs only once during script initialization.

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