在PHP中使用Heredoc有什么优势? [英] What is the advantage of using heredoc in PHP?

问题描述

在PHP中使用 heredoc 有什么好处，您可以举个例子吗?

What is the advantage of using heredoc in PHP, and can you show an example?

推荐答案

heredoc语法对我来说更干净，它对于多行字符串和避免引用问题确实很有用.回到过去，我曾经用它们来构造SQL查询:

The heredoc syntax is much cleaner to me and it is really useful for multi-line strings and avoiding quoting issues. Back in the day I used to use them to construct SQL queries:

$sql = <<<SQL
select *
  from $tablename
 where id in [$order_ids_list]
   and product_name = "widgets"
SQL;

对我来说，与使用引号相比，引入语法错误的可能性更低:

To me this has a lower probability of introducing a syntax error than using quotes:

$sql = "
select *
  from $tablename
 where id in [$order_ids_list]
   and product_name = \"widgets\"
";

另一点是避免在字符串中转义双引号:

Another point is to avoid escaping double quotes in your string:

$x = "The point of the \"argument" was to illustrate the use of here documents";

上面的pProblem是我刚才介绍的语法错误(缺少的转义引号)，与此处的文档语法相反:

The pProblem with the above is the syntax error (the missing escaped quote) I just introduced as opposed to here document syntax:

$x = <<<EOF
The point of the "argument" was to illustrate the use of here documents
EOF;

有点样式，但是我将以下内容用作定义字符串的单，双和此处文档的规则:

It is a bit of style, but I use the following as rules for single, double and here documents for defining strings:

当字符串是像'no variables here' 这样的常量时，使用
• 单引号. 当我可以将字符串放在单行上并且需要变量插值或嵌入式单引号"Today is ${user}'s birthday"
时，会使用
• 双引号
• 此处文档，用于需要格式化和变量插值的多行字符串.

• Single quotes are used when the string is a constant like 'no variables here'
• Double quotes when I can put the string on a single line and require variable interpolation or an embedded single quote "Today is ${user}'s birthday"
• Here documents for multi-line strings that require formatting and variable interpolation.

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