In PHP, what does "<<<" represent?

user_446260 0
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For example:

$sql = <<<MySQL_QUERY
heredoc operators php string
8 Answers

I found both Heredoc and Nowdoc extremelly powerfull and usefull in PHP and I am surprise that no one have so far give more example of what you can do.

First the difference between Heredoc and Nowdoc is simple,

  • Heredoc: Is like the "" double quote string you can put Variables
  • Nowdoc: Is like the '' single quote string no variable are parsed

For the following example I will only show the Heredoc, in order to make a Nowdoc just wrap the token inside single quotes -> 'TOKEN'.

Features and Advantages

  • The "" and '' can be added as much as needed and won't cause any errror
  • Easily output HTML code with dynamic variables, avoid usesell concatenations.
  • Store it in variables for letter use, can create small components and just output them.
  • The Lines are interpreted literally with '\n' hence is like writing in a doc, also useful to add
    with nl2br .

Simple Example

$a = "Hello";
$b = "World";
// HEREDOC
echo <<<HEREDOC
<strong> HEREDOC:  </strong> 
Variable A: "$a" 
Variable B: "$b"
HEREDOC;
echo '</br>';

// NOWDOC
echo <<<'NOWDOC'
<strong> NOWDOC:  </strong> 
Variable A: "$a" 
Variable B: "$b"
NOWDOC;

output

HEREDOC: Variable A: "Hello" Variable B: "World"
NOWDOC: Variable A: "$a" Variable B: "$b"

Recipes

  1. Use nl2br to add <br> for each line

This works because HEREDOC interpretes each \n as an actual line

   // HEREDOC
    echo nl2br(<<<HEREDOC
    <strong> HEREDOC:  </strong> 
    Variable A: "$a" 
    Variable B: "$b"
    HEREDOC);
    // Output HEREDOC:
    //Variable A: "Hello"
    //Variable B: "World"

  1. Create small components

         <?php
         foreach($tasks  as $task) {
             // Create an HTML like component
             $component = <<<HEREDOC
             <div class="pure-u-1-3">
                 <div class="card">
                     <div class="card-header">
                        {$task['name']}
                     </div>
                     <div class="card-body">
                         <h5 class="card-title"> {$task['state']} </h5>
                         <p class="card-text"> {$task['description']} </p>
                         <a href="view?model=todo_list&task_id={$task['id']}" class="btn btn-primary">See Task Todos</a>
                     </div>
                 </div>                    
             </div>
             HEREDOC;
             echo $component; // Output

         }

     ?>

Or just put in one string then output with 1 echo

    <?php
        $taskRendered = '';
        foreach($tasks  as $task) {
            // Create an HTML like component
            $component = <<<HEREDOC
            <div class="pure-u-1-3">
                <div class="card">
                    <div class="card-header">
                       {$task['name']}
                    </div>
                    <div class="card-body">
                        <h5 class="card-title"> {$task['state']} </h5>
                        <p class="card-text"> {$task['description']} </p>
                        <a href="view?model=todo_list&task_id={$task['id']}" class="btn btn-primary">See Task Todos</a>
                    </div>
                </div>                    
            </div>
            HEREDOC;
            $taskRendered .= $component;
        }
        echo $taskRendered; // Output
    
    ?>

Documentation

user_139039420

To get a clear idea:

$data = array(
  "Id" => 12345,
  "Cutomer" => "hi",
  "Quantity" => 2,
  "Price" => 45
);

curl_setopt($curl, CURLOPT_POSTFIELDS, json_encode($data));

If we use <<<:

$data = <<<DATA
{
  "Id": 12345,
  "Customer": "John Smith",
  "Quantity": 1,
  "Price": 10.00
}
DATA;

curl_setopt($curl, CURLOPT_POSTFIELDS, $data);

Conclusion: If we go with the 1st method we have to convert it into json_encode() which somehow requires some processing. Instead, We can use the <<< operator to save some time and get some clean code. :)

user_131154360
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