fprintf()

fprintf() — Write a formatted string to a stream.

Built-in function of PHP 8.5. The manual lists it as available in PHP 5, PHP 7, PHP 8. This page is the reference card: signature, parameters and return value, plus the changelog and the example the manual provides.

What it does

Write a string produced according to format to the stream resource specified by stream.

Signature

fprintf(resource $stream, string $format, mixed ...$values): int

Parameters

Parameter	Type	What it takes
$stream	resource	A file system pointer resource that is typically created using fopen().
$format	string	An integer followed by a dollar sign $, to specify which number argument to treat in the conversion.
...$values	mixed

Return value

Returns the length of the string written.

Example

A runnable snippet:

if (!($fp = fopen('date.txt', 'w'))) { return; } $year = 2005; $month = 5; $day = 6; fprintf($fp, "%04d-%02d-%02d", $year, $month, $day); // will write the formatted ISO date to date.txt

Changelog

Version	Change
8.5.0	A formatter that does not specify a precision now correctly treats it as a precision of 0, instead of incorrectly resetting the precision.
8.0.0	This function no longer returns false on failure.
8.0.0	Throws a ValueError if the number of arguments is zero; previously this function emitted an E_WARNING instead.
8.0.0	Throws a ValueError if [width] is less than zero or bigger than PHP_INT_MAX; previously this function emitted an E_WARNING instead.
8.0.0	Throws a ValueError if [precision] is less than zero or bigger than PHP_INT_MAX; previously this function emitted an E_WARNING instead.
8.0.0	Throws an ArgumentCountError when fewer arguments are given than required; previously this function emitted an E_WARNING instead.