String Offset Curly Brace Syntax

Also Known As

TL;DR

Explanation

PHP historically allowed both $str[0] and $str{0} to access individual characters in a string by index. The curly brace syntax $str{n} was deprecated in PHP 7.4 with a deprecation notice and fully removed in PHP 8.0 — it now produces a fatal parse error. The fix is trivial: replace {} with []. PHPStan, Rector, and PHP-CS-Fixer all detect and auto-fix this. It is purely a legacy pattern with no advantage over square brackets.

Common Misconception

Why It Matters

Common Mistakes

• $str{0} for first character — use $str[0].
• $str{strlen($str)-1} for last character — use $str[-1] (negative indexing, PHP 7.1+) or $str[strlen($str)-1].
• Not running a codebase-wide search before PHP 8 upgrade.
• Rector's PHP80MigrationRector set fixes this automatically.

Code Examples

// Deprecated PHP 7.4, fatal in PHP 8.0+:
$first = $str{0};               // Fatal error in PHP 8
$last  = $str{strlen($str)-1};  // Fatal error in PHP 8

if ($str{0} === '/') {          // Fatal error in PHP 8
    // ...
}

// Square brackets — always correct:
$first = $str[0];
$last  = $str[-1];             // Negative indexing (PHP 7.1+)
$last  = $str[strlen($str)-1]; // Or explicit

if ($str[0] === '/') {
    // ...
}

// Auto-fix with Rector:
// vendor/bin/rector process src --config rector.php
// Uses: \Rector\Php80\Rector\Array_\StringableToStringRector

References

• ↗ https://www.php.net/manual/en/migration80.deprecated.php

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