sprintf

(PHP 4, PHP 5, PHP 7)

sprintfReturn a formatted string

说明

sprintf ( string $format [, mixed $... ] ) : string

Returns a string produced according to the formatting string format.

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

...

返回值

Returns a string produced according to the formatting string format, 或者在失败时返回 FALSE.

范例

Example #1 Argument swapping

The format string supports argument numbering/swapping.

<?php
$num 
5;
$location 'tree';

$format 'There are %d monkeys in the %s';
echo 
sprintf($format$num$location);
?>

以上例程会输出:

There are 5 monkeys in the tree

However imagine we are creating a format string in a separate file, commonly because we would like to internationalize it and we rewrite it as:

<?php
$format 
'The %s contains %d monkeys';
echo 
sprintf($format$num$location);
?>

We now have a problem. The order of the placeholders in the format string does not match the order of the arguments in the code. We would like to leave the code as is and simply indicate in the format string which arguments the placeholders refer to. We would write the format string like this instead:

<?php
$format 
'The %2$s contains %1$d monkeys';
echo 
sprintf($format$num$location);
?>

An added benefit is that placeholders can be repeated without adding more arguments in the code.

<?php
$format 
'The %2$s contains %1$d monkeys.
           That\'s a nice %2$s full of %1$d monkeys.'
;
echo 
sprintf($format$num$location);
?>

When using argument swapping, the n$ position specifier must come immediately after the percent sign (%), before any other specifiers, as shown below.

Example #2 Specifying padding character

<?php
echo sprintf("%'.9d\n"123);
echo 
sprintf("%'.09d\n"123);
?>

以上例程会输出:

......123
000000123

Example #3 Position specifier with other specifiers

<?php
$format 
'The %2$s contains %1$04d monkeys';
echo 
sprintf($format$num$location);
?>

以上例程会输出:

The tree contains 0005 monkeys

Example #4 sprintf(): zero-padded integers

<?php
$isodate 
sprintf("%04d-%02d-%02d"$year$month$day);
?>

Example #5 sprintf(): formatting currency

<?php
$money1 
68.75;
$money2 54.35;
$money $money1 $money2;
echo 
$money;
echo 
"\n";
$formatted sprintf("%01.2f"$money);
echo 
$formatted;
?>

以上例程会输出:

123.1
123.10

Example #6 sprintf(): scientific notation

<?php
$number 
362525200;

echo 
sprintf("%.3e"$number);
?>

以上例程会输出:

3.625e+8

参见

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