[PHP-NOTES] note 130502 added to datetime.format

Ad Escaping characters while formatting

To escape special characters, such as `\n`, `\t`, etc., is needed usage of multiple escaping to avoid expanding the formatting key or special character itself.

In my case I needed a new line sequence `\n` to be printed in the output as is i.e. as a plain text with backslash and letter n.

In the example bellow there are used letters `Y`, `n`, `W` that without escaping are recognized as format character representing full year (`Y`), month number(`n`) and week number (`W`).

<?php
/* Escaping new line special character \n to be a plain text */

// Now
$now = new DateTime();

// Prints something like: 2025\n41
echo $now->format('Y\\\\\nW');

/* Test of various escaping sequences */

// List of formats in single quotes
$formats = [
    'YnW',  // 20251041
    'Y\nW',  // 2025n41
    'Y\\nW',  // 2025n41
    'Y\\\nW',  // 2025\1041
    'Y\\\\nW',  // 2025\1041
    'Y\\\\\nW',  // 2025\n41
    'Y\\\\\\nW',  // 2025\n41
    'Y\\\\\\\nW',  // 2025\\1041
    'Y\\\\\\\\nW',  // 2025\\1041
    'Y\\\\\\\\\nW',  // 2025\\n41
    'Y\\\\\\\\\\nW',  // 2025\\n41
];
foreach($formats as $key => $format){
  echo PHP_EOL . $key . '. format: '. var_export($format, true) ."\t".' output: '. $now->format($format);
}
?>
Prints something like:
0. format: 'YnW'  output: 20251041
1. format: 'Y\\nW'  output: 2025n41
2. format: 'Y\\nW'  output: 2025n41
3. format: 'Y\\\\nW'  output: 2025\1041
4. format: 'Y\\\\nW'  output: 2025\1041
5. format: 'Y\\\\\\nW'  output: 2025\n41
6. format: 'Y\\\\\\nW'  output: 2025\n41
7. format: 'Y\\\\\\\\nW'  output: 2025\\1041
8. format: 'Y\\\\\\\\nW'  output: 2025\\1041
9. format: 'Y\\\\\\\\\\nW'  output: 2025\\n41
10. format: 'Y\\\\\\\\\\nW'  output: 2025\\n41
----
Server IP: 45.112.84.4
Probable Submitter: 45.112.84.18 (proxied: 158.88.8.6)
----
Manual Page -- https://php.net/manual/en/datetime.format.php
Edit        -- https://main.php.net/note/edit/130502
Del: integrated  -- https://main.php.net/note/delete/130502/integrated
Del: useless     -- https://main.php.net/note/delete/130502/useless
Del: bad code    -- https://main.php.net/note/delete/130502/bad+code
Del: spam        -- https://main.php.net/note/delete/130502/spam
Del: non-english -- https://main.php.net/note/delete/130502/non-english
Del: in docs     -- https://main.php.net/note/delete/130502/in+docs
Del: other reasons-- https://main.php.net/note/delete/130502
Reject      -- https://main.php.net/note/reject/130502
Search      -- https://main.php.net/manage/user-notes.php