What is the difference between single quotes and double quotes in php

The main difference between single quotes and double quotes in PHP is variable parsing and escape character processing. Single quotes do not parse variables or escape characters, while double quotes parse variables and allow escape characters. In addition, double quotes support Heredoc and Nowdoc syntax, while single quotes do not.

The difference between single quotes and double quotes in PHP

In PHP, single quotes (') and double quotes Quotes (") are both string delimiters used to surround strings. However, there are some key differences between them:

Variable parsing:

• Single quotes: Variables in strings will not be parsed.
• Double quotes: Variables in strings will be parsed.

For example:

<code class="php">$name = 'John';
echo 'My name is $name.'; // 输出 My name is $name
echo "My name is $name."; // 输出 My name is John</code>

Escape characters:

##Single quotes: escape characters do not work.
• Double quotes: escape characters work. ##For example:

• <code class="php">echo 'This is a single-quoted string with a backslash: \n'; // 输出 This is a single-quoted string with a backslash: \n
  echo "This is a double-quoted string with a backslash: \n"; // 输出 This is a double-quoted string with a backslash:</code>

Heredoc and Nowdoc Syntax:

##Single quotes: Not supported Double quotes: Heredoc and Nowdoc are supported. Nowdoc syntax.

• Heredoc and Nowdoc is a syntax for embedding multiple lines of text in a string.
• For example:

<code class="php">// 使用双引号
$text = <<<EOT
这是使用双引号创建的多行字符串。
可以包含变量：$name
EOT;

// 使用单引号（不受支持）
$text = <<<'EOT'
这是使用单引号创建的多行字符串。
无法包含变量：$name
EOT;</code>

Other differences:

Single quotes have higher precedence than double quotes, which means that when nested strings are encountered, the outer single quotes will take precedence Double quotes. Unicode escape sequences (such as \u00A0) are supported, but single quotes are not supported

• When choosing between single quotes or double quotes, the following guidelines are usually followed:
• If If the string does not contain variables or requires escaping characters, please use single quotes.

If the string contains variables or requires Heredoc/Nowdoc syntax, please use double quotes.

The above is the detailed content of What is the difference between single quotes and double quotes in php. For more information, please follow other related articles on the PHP Chinese website!