Strings

What it is

Strings contain bytes; concatenation uses a dot.

When to use it

Use interpolation for readable messages and mb_* for Unicode character operations.

Syntax

$label = "Account {$accountId}";
$clean = trim($input);

Example

$input = "  invoice-42  ";
$reference = strtoupper(trim($input));
$containsInvoice = str_contains($reference, "INVOICE");

Common mistakes

strlen counts bytes, not Unicode characters; string concatenation is not HTML escaping.

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