Strings

• Unicode is not natively supported.
• There are no practical limits on the size of a string.
• Characters within strings may be accessed by specifying the zero-based offset of the desired character after the string in curly braces, {}.
• For backwards compatibility, square brackets, [], can be used to access characters; this syntax has been deprecated as of PHP 4.

Functions

• sprintf
• sscanf

Double-quote strings

• Variables in the string will be expanded.

Backslash escapes

\"  : Double quote
\\  : Backslash

\n  : Linefeed
\r  : Carriage return
\t  : Tab
\$  : Dollar sign

\x[0-9A-Fa-f]{1,2} : Character value in hexadecimal.
\[0-7]{1,3}        : Character value in octal.

• The backslash is treated as a regular character if it precedes any character other than the above.

Single-quote strings

• Variables in the string will not be expanded.

Backslash escapes

\'  : Single quote
\\  : Backslash

• The backslash is treated as a regular character if it precedes any character other than the above.
• To add newlines, the string literal itself must contain actual newlines (\n will not be expanded).

echo 'This is how to embed
a newline in a single-quote string.';

Heredoc text

<<<IDENTIFIER
...
IDENTIFIER[;]

• Heredoc text behaves like a double-quote string.
• Variables in the heredoc text will be expanded.
• The backslash escapes for double-quote strings can be used.
• Backslash escapes are not needed for quote characters.

• The closing identifier must begin on the first column of a line.
• An optional semicolon can be placed immediately after the closing identifier.
• The first character before the closing identifier must be a newline as defined by the operating system (\r on Macintosh, for example).
• When a text file is FTP'd in ASCII mode, the FTP server will know what kind of line ends to put in (and will do so).

echo <<<MYTEXT
This is some text
     that will be displayed.
MYTEXT

echo <<<MORE_INFO
The value of $var1 is $var1
MORE_INFO;