How PHP strings are defined and their differences

This article mainly introduces the way of the definition of PHP string and their respective differences, has a certain reference value, now share to everyone, the need for friends can refer to

• Single quotes:

Single quotation mark cannot parse variable

Single quotes cannot parse escape characters, only single quotes and backslashes themselves

Variables and variables, variables, and strings, strings, and strings can be used . Connection

• Double quotes

Double quotation marks can parse variables, variables can use special characters and {} contain

Double quotes to resolve all escape characters

Variables and variables, variables, and strings, strings, and strings can be used . Connection

$sql = "SELECT * from user where name = ' {$name} '";-->select * from user where name = ' Lisi '

$sql = ' Select ' from user where name = \ '. $name. ' \''; Higher efficiency

• The difference between single and double quotation marks

Single quote efficiency is higher than double quotation mark

• Heredoc

Functions similar to double quotation marks

$str = <<<eodexample of stringspanning multiple linesusing heredoc syntax. EOD; $str = <<< "FOOBAR" Hello world! FOOBAR;

Cannot have any other symbols before the end identifier (indent is not allowed)

• Nowdoc

Functions similar to single quotes

$str = <<< ' EOD ' Example of stringspanning multiple linesusing nowdoc syntax. EOD;