The vfprintf Function
The vfprintf function writes a string formatted according to specifiers to a file stream. The first parameter accepts a file resource, the second - a format string, the third - an array of arguments for substitution. The format string uses special characters (format specifiers) that start with the % sign and control the output formatting.
Syntax
vfprintf(resource $handle, string $format, array $args): int
Format Specifiers
| Specifier | Description |
|---|---|
%s |
String |
%d |
Signed integer (decimal) |
%u |
Unsigned integer (decimal) |
%f |
Floating-point number (locale-dependent) |
%F |
Floating-point number (non-locale-dependent) |
%c |
Character by ASCII code |
%x |
Integer in hexadecimal system (lowercase) |
%X |
Integer in hexadecimal system (uppercase) |
%o |
Integer in octal system |
%b |
Integer in binary system |
%e |
Scientific notation (lowercase) |
%E |
Scientific notation (uppercase) |
%g |
Short representation of %e or %f |
%G |
Short representation of %E or %F |
%% |
Percent sign |
Example
Writing a formatted string to a file:
<?php
$file = fopen('output.txt', 'w');
$values = [10, 20.5, 'test'];
vfprintf($file, "Number: %d, Float: %.2f, String: %s", $values);
fclose($file);
?>
Contents of the output.txt file:
'Number: 10, Float: 20.50, String: test'
Example
Using different specifiers:
<?php
$res = fopen('php://output', 'w');
$data = [15, 12.3456, 'ABCDE'];
vfprintf($res, "Hex: %x, Scientific: %.2e, Padding: '%5s'", $data);
fclose($res);
?>
Output result:
'Hex: f, Scientific: 1.23e+1, Padding: \' ABCDE\''
