PHP Tutorial – 05 – Strings

Combining strings

In PHP there are only two string operators. The first is the concatenation operator which combines two strings.

$a = "Hello";
$b = " World";
$c = $a . $b;

The second is the concatenating assignment operator that appends a string to the end of another string.

$a .= $b;

Delimiting strings

PHP strings can be delimited in four different ways. There are two single-line notations: double-quote and single-quote. The difference between them is that variables are not parsed in single-quoted strings whereas they are parsed in double-quoted strings. Single-quoted strings is prefered unless parsing is desired, because parsing strings has a small performance overhead.

echo "Hello $b"; // Hello World
echo 'Hello $b'; // Hello $b

There are also two multi-line notations: heredoc and nowdoc. These notations are mainly used to include large blocks of text.

Heredoc strings

The heredoc syntax consists of the <<< operator followed by an identifier and a new line. The string is then included and after that the identifier is used again at the start of a new line in order to close the string. Variables are parsed inside of a heredoc string, just as with double-quoted strings.

$s = <<<LABEL
Heredoc (with parsing)
LABEL;

Nowdoc strings

The syntax for the nowdoc string is the same as for the heredoc string, except that the initial identifier is enclosed in single-quotes. No parsing is done inside a nowdoc string.

$s = <<<'LABEL'
Nowdoc (without parsing)
LABEL;

Escape characters

The escape character (\) is used to write special characters, such as newline or double-quote.

When using the single-quote or nowdoc delimiter the only escape characters that work are for backslash (\\) and single-quote (\’) characters.

Recommended reading:
Sams - Teach Yourself PHP in 24 Hours

PVT book:
Handbook of C++ Syntax