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SplFileObject::fscanf

(PHP 5 >= 5.1.0, PHP 7)

SplFileObject::fscanfParses input from file according to a format

说明

public SplFileObject::fscanf ( string $format [, mixed &$... ] ) : mixed

Reads a line from the file and interprets it according to the specified format, which is described in the documentation for sprintf().

Any whitespace in the format string matches any whitespace in the line from the file. This means that even a tab \t in the format string can match a single space character in the input stream.

参数

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: %[flags][width][.precision]specifier.

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

...

The optional assigned values.

返回值

If only one parameter is passed to this method, the values parsed will be returned as an array. Otherwise, if optional parameters are passed, the function will return the number of assigned values. The optional parameters must be passed by reference.

范例

Example #1 SplFileObject::fscanf() example

<?php
$file 
= new SplFileObject("misc.txt");
while (
$userinfo $file->fscanf("%s %s %s")) {
    list (
$name$profession$countrycode) = $userinfo;
    
// Do something with $name $profession $countrycode
}
?>

Contents of users.txt

javier   argonaut    pe
hiroshi  sculptor    jp
robert   slacker     us
luigi    florist     it

参见

  • fscanf() - 从文件中格式化输入
  • sscanf() - 根据指定格式解析输入的字符
  • printf() - 输出格式化字符串
  • sprintf() - Return a formatted string

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