What is the advantage of using heredoc in PHP?

Question

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

Answer 1

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;

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\"
";

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";

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;

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

• 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.