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fprintf

Write a formatted string to a stream

Syntax

fprintf ( resource $handle , string $format [, mixed $... ] ) : int

Parameters

handle

A 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.

Argnum

An integer followed by a dollar sign $, to specify which number argument to treat in the conversion.

Flags

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).

Width

An integer that says how many characters (minimum) this conversion should result in.

Precision

A period . followed by an integer who's meaning depends on the specifier:

For e, E, f and F specifiers: this is the number of digits to be printed after the decimal point (by default, this is 6).

For g and G specifiers: this is the maximum number of significant digits to be printed.

For 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.

Note: Attempting to use a position specifier greater than PHP_INT_MAX will generate warnings.

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). The precision specifier stands for the number of digits after the decimal point.
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.
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).

Warning: The c type specifier ignores padding and width

Warning: 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
integer d, u, c, o, x, X, b
double g, G, e, E, f, F
...

Return

Returns the length of the string written.

Examples

1

<?

$filename = $_SERVER['DOCUMENT_ROOT'] . '/assets/txt/file.txt';
$mode = 'w+';

$handle = fopen($filename, $mode);
    $format = '%01.2f';
    $amount = 1234.5;
    fprintf($handle, $format, $amount);
    rewind($handle);
    $length = filesize($filename);
    $fread = fread($handle, $length);
fclose($handle);

echo $fread;

?>
1234.50

2

<?

$filename = $_SERVER['DOCUMENT_ROOT'] . '/assets/txt/file.txt';
$mode = 'w+';

$handle = fopen($filename, $mode);
    $format = '%04d-%02d-%02d';
    $year = date('Y');
    $month = date('m');
    $day = date('d');
    fprintf($handle, $format, $year, $month, $day);
    rewind($handle);
    $length = filesize($filename);
    $fread = fread($handle, $length);
fclose($handle);

echo $fread;

?>
2021-07-25

3

<?

$filename = $_SERVER['DOCUMENT_ROOT'] . '/assets/txt/file.txt';
$mode = 'w';

$handle = fopen($filename, $mode);
    $format = '%04d-%02d-%02d';
    $year = date('Y');
    $month = date('m');
    $day = date('d');
    $return = fprintf($handle, $format, $year, $month, $day);
fclose($handle);

echo $return;

?>
10

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