Difference between single-quoted and double-quoted strings in PHP?

What is the difference between single-quoted and double-quoted strings in PHP

Let’s understand what is the difference between single-quoted and double-quoted strings in PHP?

In PHP, there are two types of string literals: single-quoted strings and double-quoted strings. The main difference between them lies in how they handle the interpretation of variables and escape sequences.

Single-quoted strings:

  • Variables: Single-quoted strings treat variables literally and do not expand their values. If a variable is included within a single-quoted string, it is treated as part of the string itself.
  • Escape sequences: Only two escape sequences are recognized within single-quoted strings: \' for a literal single quote and \\ for a literal backslash. All other escape sequences are treated as regular characters.
  • The simplest way to specify a string is to enclose it in single quotes. Everything inside single quotes is treated as a plain string.
  • Example:
$name = "John";
echo 'Hello, $name'; // Output: Hello, $name

Double-quoted strings:

  • Variables: Double-quoted strings interpret variables and expand their values within the string. When a variable is included within a double-quoted string, its value is inserted in place.
  • Escape sequences: Double-quoted strings recognize various escape sequences such as \n for a new line, \t for a tab, and \" for a literal double quote. They also interpret variable interpolation using the syntax $variable.
  • Example:
$name = "John";
echo "Hello, $name"; // Output: Hello, John

Additionally, double-quoted strings offer more flexibility in string manipulation as they allow the use of complex expressions and special characters within the string. They can also include array elements and object properties directly within the string by using the curly braces {} to delimit them.

$age = 25;
echo "My name is $name and I am {$age} years old."; // Output: My name is John and I am 25 years old.

In summary, single-quoted strings are useful for simple, literal strings, while double-quoted strings provide more functionality by allowing variable interpolation and the interpretation of escape sequences.