sscanf()

The PHP sscanf() function reads a string and pulls out values according to a format you describe — it is the inverse of sprintf(). Where sprintf() builds a formatted string from variables, sscanf() takes apart a formatted string back into variables. It shines when you have text in a predictable shape (dates, coordinates, log lines, ID codes) and want clean, typed pieces without writing a regular expression.

This chapter covers the syntax, the two ways to receive results, the format specifiers you will actually use, and the common pitfalls.

Syntax

sscanf(string $string, string $format, mixed &...$vars): array|int|null

• $string — the input text to parse.
• $format — a template describing what to read, using % specifiers (the same family printf uses).
• &...$vars — optional variables, passed by reference, that receive the parsed values.

How sscanf() behaves depends on whether you pass those extra variables:

Return the values as an array

If you omit the reference arguments, sscanf() hands everything back as an array. This is the cleanest style in modern PHP and avoids passing variables by reference.

%s reads the next non-whitespace word (John), and %d reads an integer (25, stored as a real int, not the string "25"). The output is:

John
25

Assign directly into variables

Passing variables after the format assigns into them directly. In this mode the return value is the count of fields that matched, which is handy for validating input.

<?php
$input = 'John 25';
$matched = sscanf($input, '%s %d', $name, $age);

echo $matched . "\n"; // 2  (both fields were read)
echo $name . "\n";    // John
echo $age;            // 25
?>

Note: in PHP 8 the call-time & prefix (e.g. sscanf($s, $f, &$name)) was removed. Just pass the plain variable — sscanf() declares those parameters as by-reference itself.

Common format specifiers

Literal characters in the format (spaces, slashes, colons) must appear in the input too. This makes sscanf() excellent for fixed-shape data such as dates:

<?php
$date = '2026-06-21';
[$year, $month, $day] = sscanf($date, '%d-%d-%d');

printf("Year=%d Month=%d Day=%d", $year, $month, $day);
// Year=2026 Month=6 Day=21
?>

When to use sscanf() vs. alternatives

• Reach for sscanf() when the format is fixed and simple and you want typed results in one line.
• Use explode() when you only need to split on a delimiter and keep everything as strings.
• Use preg_match() when the structure is irregular or needs validation rules that go beyond simple field types.
• To do the reverse — assemble a formatted string — use sprintf() or printf().

To read formatted input directly from a file instead of a string, see fscanf(), which works the same way line by line.

Gotchas

• %s stops at whitespace. It will not capture a multi-word value. To read the rest of a line, use a scanset like %[^\n].
• A non-matching field aborts the rest. If %d is expected but the input has letters, parsing stops; the count return value lets you detect this.
• Unmatched trailing variables become null. Always check the returned count before trusting later variables.

Practice