PHP string definition methods and their differences

This article mainly introduces the definition methods of PHP strings and their differences. It has certain reference value. Now I share it with you. Friends in need can refer to it

• Single quotes:

## Single quotes cannot parse variables

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

You can use

. to connect variables and variables, variables and strings, and strings and strings

• # Double quotation marks

This dual quotation can resolve variables, variables can use special characters and {} contain

dual quotation marks to analyze all transfers Characters

Variables and variables, variables and strings, strings and strings can be connected using

.

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

$ sql = 'select * from user where name = \''.$name.'\''; //More efficient

• The difference between single quotes and double quotes

# Single quotation number is higher than the double quotes

## The function is similar to the double quotes

#

$str = <<<EODExample of string
spanning multiple lines
using heredoc syntax.
EOD;
$str = <<<"FOOBAR"Hello World!FOOBAR;

There cannot be any other symbols before the end identifier (indentation is not allowed)

• nowdoc

Function is similar to single quotes

$str = <<<&#39;EOD&#39;Example of string
spanning multiple lines
using nowdoc syntax.
EOD;

• ##Both are used to process large text

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