Php/docs/function.fprintf

• PHP Manual
• 字符串 函数
• 将格式化后的字符串写入到流

fprintf

(PHP 5, PHP 7)

fprintf — 将格式化后的字符串写入到流

说明

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

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。

参数

handle

文件系统指针，是典型地由 fopen() 创建的 resource(资源)。

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	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).

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.

Specifiers

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).

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 Handling

Type	Specifiers
string	s
integer	d, u, c, o, x, X, b
double	g, G, e, E, f, F

...

返回值

返回写入的字符串长度。

范例

Example #1 fprintf(): zero-padded integers

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

Example #2 fprintf(): formatting currency

<?phpif (!($fp = fopen('currency.txt', 'w'))) {    return;}$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.txtecho "wrote $len bytes to currency.txt";// use the return value of fprintf to determine how many bytes we wrote?>

参见

• printf() - 输出格式化字符串
• sprintf() - Return a formatted string
• vprintf() - 输出格式化字符串
• vsprintf() - 返回格式化字符串
• vfprintf() - 将格式化字符串写入流
• sscanf() - 根据指定格式解析输入的字符
• fscanf() - 从文件中格式化输入
• number_format() - 以千位分隔符方式格式化一个数字
• date() - 格式化一个本地时间／日期