(PHP 5, PHP 7, PHP 8)
fprintf — Write a formatted string to a stream
Write a string produced according to format to the
stream resource specified by stream.
streamA file system pointer resource that is typically created using fopen().
format
The format string is composed of zero or more directives:
ordinary characters (excluding %) that are
copied directly to the result and conversion
specifications, each of which results in fetching its
own parameter.
A conversion specification follows this prototype:
%[argnum$][flags][width][.precision]specifier.
An integer followed by a dollar sign $,
to specify which number argument to treat in the conversion.
| Flag | Description |
|---|---|
- |
Left-justify within the given field width; Right justification is the default |
+ |
Prefix positive numbers with a plus sign
+; Default only negative
are prefixed with a negative sign.
|
(space) |
Pads the result with spaces. This is the default. |
0 |
Only left-pads numbers with zeros.
With s specifiers this can
also right-pad with zeros.
|
'(char) |
Pads the result with the character (char). |
Either an integer that says how many characters (minimum)
this conversion should result in, or *.
If * is used, then the width is supplied
as an additional integer value preceding the one formatted
by the specifier.
A period . optionally followed by
either an integer or *,
whose meaning depends on the specifier:
e, E,
f and F
specifiers: this is the number of digits to be printed
after the decimal point (by default, this is 6).
g, G,
h and H
specifiers: this is the maximum number of significant
digits to be printed.
s specifier: it acts as a cutoff point,
setting a maximum character limit to the string.
Note: If the period is specified without an explicit value for precision, 0 is assumed. If
*is used, the precision is supplied as an additional integer value preceding the one formatted by the specifier.
| Specifier | Description |
|---|---|
% |
A literal percent character. No argument is required. |
b |
The argument is treated as an integer and presented as a binary number. |
c |
The argument is treated as an integer and presented as the character with that ASCII. |
d |
The argument is treated as an integer and presented as a (signed) decimal number. |
e |
The argument is treated as scientific notation (e.g. 1.2e+2). |
E |
Like the e specifier but uses
uppercase letter (e.g. 1.2E+2).
|
f |
The argument is treated as a float and presented as a floating-point number (locale aware). |
F |
The argument is treated as a float and presented as a floating-point number (non-locale aware). |
g |
General format. Let P equal the precision if nonzero, 6 if the precision is omitted, or 1 if the precision is zero. Then, if a conversion with style E would have an exponent of X: If P > X ≥ −4, the conversion is with style f and precision P − (X + 1). Otherwise, the conversion is with style e and precision P − 1. |
G |
Like the g specifier but uses
E and f.
|
h |
Like the g specifier but uses F.
Available as of PHP 8.0.0.
|
H |
Like the g specifier but uses
E and F. Available as of PHP 8.0.0.
|
o |
The argument is treated as an integer and presented as an octal number. |
s |
The argument is treated and presented as a string. |
u |
The argument is treated as an integer and presented as an unsigned decimal number. |
x |
The argument is treated as an integer and presented as a hexadecimal number (with lowercase letters). |
X |
The argument is treated as an integer and presented as a hexadecimal number (with uppercase letters). |
The c type specifier ignores padding and width
Attempting to use a combination of the string and width specifiers with character sets that require more than one byte per character may result in unexpected results
Variables will be co-erced to a suitable type for the specifier:
| Type | Specifiers |
|---|---|
| string | s |
| int |
d,
u,
c,
o,
x,
X,
b
|
| float |
e,
E,
f,
F,
g,
G,
h,
H
|
values
Returns the length of the string written.
As of PHP 8.0.0, a ValueError is thrown if the number of arguments is zero.
Prior to PHP 8.0.0, a E_WARNING was emitted instead.
As of PHP 8.0.0, a ValueError is thrown if [width] is less than zero or bigger than PHP_INT_MAX.
Prior to PHP 8.0.0, a E_WARNING was emitted instead.
As of PHP 8.0.0, a ValueError is thrown if [precision] is less than zero or bigger than PHP_INT_MAX.
Prior to PHP 8.0.0, a E_WARNING was emitted instead.
As of PHP 8.0.0, a ArgumentCountError is thrown when less arguments are given than required.
Prior to PHP 8.0.0, false was returned and a E_WARNING emitted instead.
| Version | Description |
|---|---|
| 8.0.0 |
This function no longer returns false on failure.
|
| 8.0.0 |
Throw a ValueError if the number of arguments is zero;
previously this function emitted a E_WARNING instead.
|
| 8.0.0 |
Throw a ValueError if [width] is less than zero or bigger than PHP_INT_MAX;
previously this function emitted a E_WARNING instead.
|
| 8.0.0 |
Throw a ValueError if [precision] is less than zero or bigger than PHP_INT_MAX;
previously this function emitted a E_WARNING instead.
|
| 8.0.0 |
Throw a ArgumentCountError when less arguments are given than required;
previously this function emitted a E_WARNING instead.
|
Example #1 fprintf(): zero-padded integers
<?php
if (!($fp = fopen('date.txt', 'w'))) {
return;
}
fprintf($fp, "%04d-%02d-%02d", $year, $month, $day);
// will write the formatted ISO date to date.txt
?>Example #2 fprintf(): formatting currency
<?php
if (!($fp = fopen('currency.txt', 'w'))) {
return;
}
$money1 = 68.75;
$money2 = 54.35;
$money = $money1 + $money2;
// echo $money will output "123.1";
$len = fprintf($fp, '%01.2f', $money);
// will write "123.10" to currency.txt
echo "wrote $len bytes to currency.txt";
// use the return value of fprintf to determine how many bytes we wrote
?>