(PHP 5, PHP 7)
fprintf — 将格式化后的字符串写入到流
写入一个根据 format 格式化后的字符串到
由 handle 句柄打开的流中。
handleformatThe 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 | 说明 |
|---|---|
| - | 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). |
An integer that says how many characters (minimum) this conversion should result in.
A period . followed by an integer who's meaning depends on the specifier:
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_MAXwill generate warnings.
| Specifier | 说明 |
|---|---|
| % | 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 since PHP 5.2.1. In earlier versions, it was taken as number of significant digits (one less). |
| 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). Available as of PHP 5.0.3. |
| 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). |
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 |
| integer | d, u, c, o, x, X, b |
| double | g, G, e, E, f, F |
...
返回写入的字符串长度。
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
?>