sprintf

(PHP 4, PHP 5, PHP 7, PHP 8)

sprintf — 返回格式化字符串

说明

sprintf ( string $format , mixed ...$values ) : string

返回一个根据格式化字符串 format 生成的字符串。

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: %[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, G, h and H 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).
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.
h Like the g specifier but uses F. Available as of PHP 8.0.0.
H Like the g specifier but uses E and F. Available as of PHP 8.0.0.
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
int d, u, c, o, x, X, b
float e, E, f, F, g, G, h, H

values

返回值

返回一个根据格式化字符串 format 生成的字符串。

更新日志

版本 说明
8.0.0 此函数失败时不再返回 false 。

范例

Example #1 参数替换

支持按顺序用参数替换格式字符串里的占位符。

<?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

假设，我们想把它国际化，在一个单独的文件中创建格式字符串，我们将它重写为：

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

我们现在有一个问题。 格式字符串中占位符的顺序与代码中参数的顺序不匹配。 我们希望保持代码原样，并在格式字符串中简单地指出占位符引用的参数。 我们可以这样写格式化字符串：

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

另外一个好处是占位符可以重复使用，而无需在代码中添加更多参数。

<?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);
?>

当使用参数替换时，n$ 位置指示符 必须紧跟在百分号（%）之后，在任何其他指示符之前，如下所示。

Example #2 指定填充字符

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

以上例程会输出：

......123
000000123

Example #3 位置说明符与其他说明符

<?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(): 零填充整数

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

Example #5 sprintf(): 货币格式

<?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(): 科学记数法

<?php
$number = 362525200;

echo sprintf("%.3e", $number);
?>

以上例程会输出：

3.625e+8

参见

User Contributed Notes

Mirek Z... 15-Mar-2020 07:19
I've performed a simple speed test. sprintf against PHP string concatenation operator. Test was performed on PHP 7.3 for 1 million interations.

I run this several times and what I've noted that string concatenation took about 2.9 seconds, sprintf took 4.3 seconds.
I was thinking about what is faster, what is better to do when we're going to format our string (for example, the message to the user or for log purposes) containing some variables values. Is it better to concatenate string with variables using operator (dot ".") or to use sprintf. The answer is: when you do not plan to implement any multilanguage mechanisms and feel good with hardcoding some texts, the "dot" is almost 1.5 times faster!

Here's the code:

echo 'Start' . PHP_EOL;
$vS_text = 'some text';
$vS = '';
$vf = microtime(true);
for ($vI = 0; $vI < 1000000; $vI++) {
    $vS = 'Start ' . $vI . ' ' . $vS_text . ' ' . $vf . ' end';
}
$vf = microtime(true) - $vf;
echo 'Concat:' . $vf . PHP_EOL;
$vS = '';
$vf = microtime(true);
for ($vI = 0; $vI < 1000000; $vI++) {
    $vS = sprintf('Start %d %s %f end', $vI, $vS_text, $vf);
}
$vf = microtime(true) - $vf;
echo 'Spritf:' . $vf . PHP_EOL;
Anderson 18-Nov-2019 09:23
The old "monkey" example which helped me a lot has sadly disappeared.

I'll Re-post it in comment as a memory.

<?php
$n =  43951789;
$u = -43951789;
$c = 65; // ASCII 65 is 'A'

// notice the double %%, this prints a literal '%' character
printf("%%b = '%b'\n", $n); // binary representation
printf("%%c = '%c'\n", $c); // print the ascii character, same as chr() function
printf("%%d = '%d'\n", $n); // standard integer representation
printf("%%e = '%e'\n", $n); // scientific notation
printf("%%u = '%u'\n", $n); // unsigned integer representation of a positive integer
printf("%%u = '%u'\n", $u); // unsigned integer representation of a negative integer
printf("%%f = '%f'\n", $n); // floating point representation
printf("%%o = '%o'\n", $n); // octal representation
printf("%%s = '%s'\n", $n); // string representation
printf("%%x = '%x'\n", $n); // hexadecimal representation (lower-case)
printf("%%X = '%X'\n", $n); // hexadecimal representation (upper-case)

printf("%%+d = '%+d'\n", $n); // sign specifier on a positive integer
printf("%%+d = '%+d'\n", $u); // sign specifier on a negative integer

/*
%b = '10100111101010011010101101'
%c = 'A'
%d = '43951789'
%e = '4.395179e+7'
%u = '43951789'
%u = '18446744073665599827'
%f = '43951789.000000'
%o = '247523255'
%s = '43951789'
%x = '29ea6ad'
%X = '29EA6AD'
%+d = '+43951789'
%+d = '-43951789'
*/

$s = 'monkey';
$t = 'many monkeys';

printf("[%s]\n",      $s); // standard string output
printf("[%10s]\n",    $s); // right-justification with spaces
printf("[%-10s]\n",   $s); // left-justification with spaces
printf("[%010s]\n",   $s); // zero-padding works on strings too
printf("[%'#10s]\n",  $s); // use the custom padding character '#'
printf("[%10.10s]\n", $t); // left-justification but with a cutoff of 10 characters

/*
[monkey]
[    monkey]
[monkey    ]
[0000monkey]
[####monkey]
[many monke]
*/
?>
Anonymous 13-Dec-2018 02:26
I have written a wrapper for sprintf. Add a new %S  (upper case s) where the number indicates the number of characters and not bytes.
This is useful for formatting utf-8 strings.

<?php
function SacSprintf( $format) {
        $argv = func_get_args() ;
        array_shift($argv) ;

        $offset = 0;
        $i = 0;
        while( preg_match("^A%[+-]*[.]*([0-9.]*)([a-z])^Ai", $format, $match, PREG_OFFSET_CAPTURE, $offset)) {
                if( $match[2][0] == 'S') {
                        if( $match[1][0] != '') {
                                $t1 = explode('.', $match[1][0]);
                                $t1[0] = intval($t1[0]) + strlen($argv[$i]) - strlen(utf8_decode($argv[$i]));
                                $l1 = strlen($match[1][0]);
                                $t2 = implode('.', $t1);
                                $l2 = strlen($t2) - $l1;
                                $format = substr_replace( $format, $t2, $match[1][1], strlen($match[1][0]));
                                $offset += $l2;
                                $match[2][1] += $l2;
                        }   
                        $format[$match[2][1]] = 's';
                }   
                $offset += $match[2][1];
                $i++;
        }   
        return vsprintf($format, $argv) ;
}

echo "<pre>\n";
echo "      1234567890123456789012345678901234567890\n";
echo sprintf("Hola, %-20s is my name\n", "José Luis jiménez");
echo SacSprintf("Hola, %-20S is my name\n", "José Luis jiménez");
echo "</pre>\n";
?>

The output will be:
      1234567890123456789012345678901234567890
Hola, José Luis jiménez  is my name
Hola, José Luis jiménez    is my name
Nathan Alan 19-Feb-2017 11:03
Just wanted to add that to get the remaining text from the string, you need to add the following as a variable in your scanf

%[ -~]

Example:

sscanf($sql, "[%d,%d]%[ -~]", $sheet_id, $column, $remaining_sql);
Anonymous 03-Jan-2017 10:02
Be cafeful while trying to refactor longer strings with repeated placeholders like

    sprintf("Hi %s. Your name is %s", $name, $name);

to use argument numbering:

   sprintf("Hi %1$s. Your name is %1$s", $name);

This will nuke you at **runtime**, because of `$s` thing being handled as variable. If you got no $s for substitution, notice will be thrown.

The solution is to use single quotes to prevent variable substitution in string:

   sprintf('Hi %1$s. Your name is %1$s', $name);

If you need variable substitution, then you'd need to split your string to keep it in single quotes:

   sprintf("Hi " . '%1$s' . ". Your {$variable} is " . '%1$s', $name);
Sam Bull 23-Oct-2015 02:35
Fix for sprintfn function for named arguments (http://php.net/manual/en/function.sprintf.php#94608):

Change the first line from:
  $arg_nums = array_slice(array_flip(array_keys(array(0 => 0) + $args)), 1);
to:
  $arg_nums = array_keys($args);
  array_unshift($arg_nums, 0);
  $arg_nums = array_flip(array_slice($arg_nums, 1, NULL, true));
nmmm at nmmm dot nu 08-Apr-2015 07:31
php printf and sprintf not seems to support star "*" formatting.

here is an example:

printf("%*d\n",3,5);

this will print just "d" instead of "<two spaces>5"
kontakt at myseosolution dot de 26-Feb-2015 10:34
There are already some comments on using sprintf to force leading leading zeros but the examples only include integers. I needed leading zeros on floating point numbers and was surprised that it didn't work as expected.

Example:
<?php
sprintf('%02d', 1);
?>

This will result in 01. However, trying the same for a float with precision doesn't work:

<?php
sprintf('%02.2f', 1);
?>

Yields 1.00.

This threw me a little off. To get the desired result, one needs to add the precision (2) and the length of the decimal seperator "." (1). So the correct pattern would be

<?php
sprintf('%05.2f', 1);
?>

Output: 01.00

Please see http://stackoverflow.com/a/28739819/413531 for a more detailed explanation.
john at jbwalker dot com 24-May-2014 12:24
I couldn't find what should be a WARNING in the documentation above, that if you have more specifiers than variables to match them sprintf returns NOTHING. This fact, IMHO, should also be noted under return values.
hdimac at gmail dot com 14-Apr-2014 04:00
In the examples, is being shown printf, but it should say sprintf, which is the function being explained... just a simple edition mistake.
ivan at php dot net 28-Dec-2013 08:13
There is a minor issue in a code of mb_vsprintf function from viktor at textalk dot com.

In "truncate $arg" section the following line:
  $arg = mb_substr($precision,0,$precision,$encoding);
needs to be replaced with:
  $arg = mb_substr($arg,0,$precision,$encoding);
Alex R. Gibbs 25-Jan-2013 08:17
1.  A plus sign ('+') means put a '+' before positive numbers while a minus sign ('-') means left justify.  The documentation incorrectly states that they are interchangeable.  They produce unique results that can be combined:

<?php
echo sprintf ("|%+4d|%+4d|\n",   1, -1);
echo sprintf ("|%-4d|%-4d|\n",   1, -1);
echo sprintf ("|%+-4d|%+-4d|\n", 1, -1);
?>

outputs:

|  +1|  -1|
|1   |-1  |
|+1  |-1  |

2.  Padding with a '0' is different than padding with other characters.  Zeros will only be added at the front of a number, after any sign.  Other characters will be added before the sign, or after the number:

<?php
echo sprintf ("|%04d|\n",   -2);
echo sprintf ("|%':4d|\n",  -2);
echo sprintf ("|%-':4d|\n", -2);

// Specifying both "-" and "0" creates a conflict with unexpected results:
echo sprintf ("|%-04d|\n",  -2);

// Padding with other digits behaves like other non-zero characters:
echo sprintf ("|%-'14d|\n", -2);
echo sprintf ("|%-'04d|\n", -2);
?>

outputs:

|-002|
|::-2|
|-2::|
|-2  |
|-211|
|-2  |
ignat dot scheglovskiy at gmail dot com 10-Oct-2012 08:47
Here is an example how alignment, padding and precision specifier can be used to print formatted list of items:

<?php

$out = "The Books\n";
$books = array("Book 1", "Book 2", "Book 3");
$pages = array("123 pages ", "234 pages", "345 pages");
for ($i = 0; $i < count($books); $i++) {
    $out .= sprintf("%'.-20s%'.7.4s\n", $books[$i], $pages[$i]);
}
echo $out;

// Outputs:
//
// The Books
// Book 1.................123
// Book 2.................234
// Book 3.................345
?>
Hayley Watson 07-Jun-2012 11:21
If you use argument numbering, then format specifications with the same number get the same argument; this can save repeating the argument in the function call.

<?php

$pattern = '%1$s %1$\'#10s %1$s!';

printf($pattern, "badgers");
?>
krzysiek dot 333 at gmail dot com - zryty dot hekko dot pl 20-Aug-2011 12:48
Encoding and decoding IP adress to format: 1A2B3C4D (mysql column: char(8) )

<?php
function encode_ip($dotquad_ip)
{
    $ip_sep = explode('.', $dotquad_ip);
    return sprintf('%02x%02x%02x%02x', $ip_sep[0], $ip_sep[1], $ip_sep[2], $ip_sep[3]);
}

function decode_ip($int_ip)
{
    $hexipbang = explode('.', chunk_split($int_ip, 2, '.'));
    return hexdec($hexipbang[0]). '.' . hexdec($hexipbang[1]) . '.' . hexdec($hexipbang[2]) . '.' . hexdec($hexipbang[3]);
}
?>
timo dot frenay at gmail dot com 02-May-2011 05:38
Here is how to print a floating point number with 16 significant digits regardless of magnitude:

<?php
    $result = sprintf(sprintf('%%.%dF', max(15 - floor(log10($value)), 0)), $value);
?>

This works more reliably than doing something like sprintf('%.15F', $value) as the latter may cut off significant digits for very small numbers, or prints bogus digits (meaning extra digits beyond what can reliably be represented in a floating point number) for very large numbers.
carmageddon at gmail dot com 02-Feb-2011 06:38
If you want to convert a decimal (integer) number into constant length binary number in lets say 9 bits, use this:

$binary = sprintf('%08b', $number );

for example:
<?php
$bin = sprintf('%08b',511 );
echo $bin."\n";
?>

would output 111111111
And 2 would output 00000010

I know the leading zeros are useful to me, perhaps they are to someone else too.
dwieeb at gmail dot com 01-Sep-2010 11:54
If you use the default padding specifier (a space) and then print it to HTML, you will notice that HTML does not display the multiple spaces correctly. This is because any sequence of white-space is treated as a single space.

To overcome this, I wrote a simple function that replaces all the spaces in the string returned by sprintf() with the character entity reference "&nbsp;" to achieve non-breaking space in strings returned by sprintf()

<?php
//Here is the function:
function sprintf_nbsp() {
   $args = func_get_args();
   return str_replace(' ', '&nbsp;', vsprintf(array_shift($args), array_values($args)));
}

//Usage (exactly like sprintf):
$format = 'The %d monkeys are attacking the [%10s]!';
$str = sprintf_nbsp($format, 15, 'zoo');
echo $str;
?>

The above example will output:
The 15 monkeys are attacking the [       zoo]!

<?php
//The variation that prints the string instead of returning it:
function printf_nbsp() {
   $args = func_get_args();
   echo str_replace(' ', '&nbsp;', vsprintf(array_shift($args), array_values($args)));
}
?>
geertdd at gmail dot com 01-Sep-2010 12:53
Note that when using a sign specifier, the number zero is considered positive and a "+" sign will be prepended to it.

<?php
printf('%+d', 0); // +0
?>
nate at frickenate dot com 13-Nov-2009 11:45
Here's a clean, working version of functions to allow using named arguments instead of numeric ones. ex: instead of sprintf('%1$s', 'Joe');, we can use sprintf('%name$s', array('name' => 'Joe'));. I've provided 2 different versions: the first uses the php-like syntax (ex: %name$s), while the second uses the python syntax (ex: %(name)s).

<?php

/**
 * version of sprintf for cases where named arguments are desired (php syntax)
 *
 * with sprintf: sprintf('second: %2$s ; first: %1$s', '1st', '2nd');
 *
 * with sprintfn: sprintfn('second: %second$s ; first: %first$s', array(
 *  'first' => '1st',
 *  'second'=> '2nd'
 * ));
 *
 * @param string $format sprintf format string, with any number of named arguments
 * @param array $args array of [ 'arg_name' => 'arg value', ... ] replacements to be made
 * @return string|false result of sprintf call, or bool false on error
 */
function sprintfn ($format, array $args = array()) {
    // map of argument names to their corresponding sprintf numeric argument value
    $arg_nums = array_slice(array_flip(array_keys(array(0 => 0) + $args)), 1);

    // find the next named argument. each search starts at the end of the previous replacement.
    for ($pos = 0; preg_match('/(?<=%)([a-zA-Z_]\w*)(?=\$)/', $format, $match, PREG_OFFSET_CAPTURE, $pos);) {
        $arg_pos = $match[0][1];
        $arg_len = strlen($match[0][0]);
        $arg_key = $match[1][0];

        // programmer did not supply a value for the named argument found in the format string
        if (! array_key_exists($arg_key, $arg_nums)) {
            user_error("sprintfn(): Missing argument '${arg_key}'", E_USER_WARNING);
            return false;
        }

        // replace the named argument with the corresponding numeric one
        $format = substr_replace($format, $replace = $arg_nums[$arg_key], $arg_pos, $arg_len);
        $pos = $arg_pos + strlen($replace); // skip to end of replacement for next iteration
    }

    return vsprintf($format, array_values($args));
}

/**
 * version of sprintf for cases where named arguments are desired (python syntax)
 *
 * with sprintf: sprintf('second: %2$s ; first: %1$s', '1st', '2nd');
 *
 * with sprintfn: sprintfn('second: %(second)s ; first: %(first)s', array(
 *  'first' => '1st',
 *  'second'=> '2nd'
 * ));
 *
 * @param string $format sprintf format string, with any number of named arguments
 * @param array $args array of [ 'arg_name' => 'arg value', ... ] replacements to be made
 * @return string|false result of sprintf call, or bool false on error
 */
function sprintfn ($format, array $args = array()) {
    // map of argument names to their corresponding sprintf numeric argument value
    $arg_nums = array_slice(array_flip(array_keys(array(0 => 0) + $args)), 1);

    // find the next named argument. each search starts at the end of the previous replacement.
    for ($pos = 0; preg_match('/(?<=%)\(([a-zA-Z_]\w*)\)/', $format, $match, PREG_OFFSET_CAPTURE, $pos);) {
        $arg_pos = $match[0][1];
        $arg_len = strlen($match[0][0]);
        $arg_key = $match[1][0];

        // programmer did not supply a value for the named argument found in the format string
        if (! array_key_exists($arg_key, $arg_nums)) {
            user_error("sprintfn(): Missing argument '${arg_key}'", E_USER_WARNING);
            return false;
        }

        // replace the named argument with the corresponding numeric one
        $format = substr_replace($format, $replace = $arg_nums[$arg_key] . '$', $arg_pos, $arg_len);
        $pos = $arg_pos + strlen($replace); // skip to end of replacement for next iteration
    }

    return vsprintf($format, array_values($args));
}

?>
Astone 15-Sep-2009 11:41
When you're using Google translator, you have to 'escape' the 'conversion specifications' by putting <span class="notranslate"></span> around them.

Like this:

<?php

function getGoogleTranslation($sString, $bEscapeParams = true)
{
    // "escape" sprintf paramerters
    if ($bEscapeParams)
    {
        $sPatern = '/(?:%%|%(?:[0-9]+\$)?[+-]?(?:[ 0]|\'.)?-?[0-9]*(?:\.[0-9]+)?[bcdeufFosxX])/';       
        $sEscapeString = '<span class="notranslate">$0</span>';
        $sString = preg_replace($sPatern, $sEscapeString, $sString);
    }

    // Compose data array (English to Dutch)
    $aData = array(
        'v'            => '1.0',
        'q'            => $sString,
        'langpair'    => 'en|nl',
    );

    // Initialize connection
    $rService = curl_init();
   
    // Connection settings
    curl_setopt($rService, CURLOPT_URL, 'http://ajax.googleapis.com/ajax/services/language/translate');
    curl_setopt($rService, CURLOPT_RETURNTRANSFER, true);
    curl_setopt($rService, CURLOPT_POSTFIELDS, $aData);
   
    // Execute request
    $sResponse = curl_exec($rService);

    // Close connection
    curl_close($rService);
   
    // Extract text from JSON response
    $oResponse = json_decode($sResponse);
    if (isset($oResponse->responseData->translatedText))
    {
        $sTranslation = $oResponse->responseData->translatedText;
    }
    else
    {
        // If some error occured, use the original string
        $sTranslation = $sString;
    }
   
    // Replace "notranslate" tags
    if ($bEscapeParams)
    {
        $sEscapePatern = '/<span class="notranslate">([^<]*)<\/span>/';
        $sTranslation = preg_replace($sEscapePatern, '$1', $sTranslation);
    }
   
    // Return result
    return $sTranslation;
}

?>

Thanks to MelTraX for defining the RegExp!
jfgrissom at gmail dot com 11-Jul-2009 09:51
I had a nightmare trying to find the two's complement of a 32 bit number.

I got this from http://www.webmasterworld.com/forum88/13334.htm (credit where credit is due... =P  )

Quote: ...find out the 2's complement of any number, which is -(pow(2, n) - N) where n is the number of bits and N is the number for which to find out its 2's complement.

This worked magic for me... previously I was trying to use

sprintf ("%b",$32BitDecimal);
But it always returned 10000000000000000000000 when the $32BitDecimal value got above 2,000,000,000.

This -(pow(2, n) - N)
Worked remarkably well and was very accurate.

Hope this helps someone fighting with two's complement in PHP.
John Walker 09-Jul-2009 05:56
To add to other notes below about floating point problems, I noted that %f and %F will apparently output a maximum precision of 6 as a default so you have to specify 1.15f (eg) if you need more.

In my case, the input (from MySQL) was a string with 15 digits of precision that was displayed with 6. Likely what happens is that the rounding occurs in the conversion to a float before it is displayed. Displaying it as 1.15f (or in my case, %s) shows the correct number.
viktor at textalk dot com 18-Feb-2009 08:16
A more complete and working version of mb_sprintf and mb_vsprintf. It should work with any "ASCII preserving" encoding such as UTF-8 and all the ISO-8859 charsets. It handles sign, padding, alignment, width and precision. Argument swapping is not handled.

<?php
if (!function_exists('mb_sprintf')) {
  function mb_sprintf($format) {
      $argv = func_get_args() ;
      array_shift($argv) ;
      return mb_vsprintf($format, $argv) ;
  }
}
if (!function_exists('mb_vsprintf')) {
  /**
   * Works with all encodings in format and arguments.
   * Supported: Sign, padding, alignment, width and precision.
   * Not supported: Argument swapping.
   */
  function mb_vsprintf($format, $argv, $encoding=null) {
      if (is_null($encoding))
          $encoding = mb_internal_encoding();

      // Use UTF-8 in the format so we can use the u flag in preg_split
      $format = mb_convert_encoding($format, 'UTF-8', $encoding);

      $newformat = ""; // build a new format in UTF-8
      $newargv = array(); // unhandled args in unchanged encoding

      while ($format !== "") {
     
        // Split the format in two parts: $pre and $post by the first %-directive
        // We get also the matched groups
        list ($pre, $sign, $filler, $align, $size, $precision, $type, $post) =
            preg_split("!\%(\+?)('.|[0 ]|)(-?)([1-9][0-9]*|)(\.[1-9][0-9]*|)([%a-zA-Z])!u",
                       $format, 2, PREG_SPLIT_DELIM_CAPTURE) ;

        $newformat .= mb_convert_encoding($pre, $encoding, 'UTF-8');
       
        if ($type == '') {
          // didn't match. do nothing. this is the last iteration.
        }
        elseif ($type == '%') {
          // an escaped %
          $newformat .= '%%';
        }
        elseif ($type == 's') {
          $arg = array_shift($argv);
          $arg = mb_convert_encoding($arg, 'UTF-8', $encoding);
          $padding_pre = '';
          $padding_post = '';
         
          // truncate $arg
          if ($precision !== '') {
            $precision = intval(substr($precision,1));
            if ($precision > 0 && mb_strlen($arg,$encoding) > $precision)
              $arg = mb_substr($precision,0,$precision,$encoding);
          }
         
          // define padding
          if ($size > 0) {
            $arglen = mb_strlen($arg, $encoding);
            if ($arglen < $size) {
              if($filler==='')
                  $filler = ' ';
              if ($align == '-')
                  $padding_post = str_repeat($filler, $size - $arglen);
              else
                  $padding_pre = str_repeat($filler, $size - $arglen);
            }
          }
         
          // escape % and pass it forward
          $newformat .= $padding_pre . str_replace('%', '%%', $arg) . $padding_post;
        }
        else {
          // another type, pass forward
          $newformat .= "%$sign$filler$align$size$precision$type";
          $newargv[] = array_shift($argv);
        }
        $format = strval($post);
      }
      // Convert new format back from UTF-8 to the original encoding
      $newformat = mb_convert_encoding($newformat, $encoding, 'UTF-8');
      return vsprintf($newformat, $newargv);
  }
}
?>
splogamurugan at gmail dot com 06-Feb-2009 05:59
$format = 'There are %1$d monkeys in the %s and %s ';
printf($format, 100, 'Chennai', 'Bangalore');

Expecting to output
"There are 100 monkeys in the Chennai and bangalore"

But, this will output
"There are 100 monkeys in the 100 and Chennai"

Because, the second and Third specifiers takes 1rst and 2nd arguments. Because it is not assigned with any arguments.
remy dot damour at -please-no-spam-laposte dot net 15-Jan-2009 11:15
With printf() and sprintf() functions, escape character is not backslash '\' but rather '%'.

Ie. to print '%' character you need to escape it with itself:
<?php
printf('%%%s%%', 'koko'); #output: '%koko%'
?>
php at mikeboers dot com 01-Oct-2008 01:42
And continuing on the same theme of a key-based sprintf...

I'm roughly (I can see a couple cases where it comes out wierd) copying the syntax of Python's string formatting with a dictionary. The improvement over the several past attempts is that this one still respects all of the formating options, as you can see in my example.

And the error handling is really crappy (just an echo). I just threw this together so do with it what you will. =]

<?php

function sprintf_array($string, $array)
{
    $keys    = array_keys($array);
    $keysmap = array_flip($keys);
    $values  = array_values($array);
   
    while (preg_match('/%\(([a-zA-Z0-9_ -]+)\)/', $string, $m))
    {   
        if (!isset($keysmap[$m[1]]))
        {
            echo "No key $m[1]\n";
            return false;
        }
       
        $string = str_replace($m[0], '%' . ($keysmap[$m[1]] + 1) . '$', $string);
    }
   
    array_unshift($values, $string);
    var_dump($values);
    return call_user_func_array('sprintf', $values);
}

echo sprintf_array('4 digit padded number: %(num)04d ', array('num' => 42));

?>

Cheers!
scott dot gardner at mac dot com 10-Jan-2008 01:22
In the last example of Example#6, there is an error regarding the output.

printf("[%10.10s]\n", $t); // left-justification but with a cutoff of 10 characters

This outputs right-justified.

In order to output left-justified:

printf("[%-10.10s]\n", $t);
ian dot w dot davis at gmail dot com 30-May-2005 07:03
Just to elaborate on downright's point about different meanings for %f, it appears the behavior changed significantly as of 4.3.7, rather than just being different on different platforms. Previously, the width specifier gave the number of characters allowed BEFORE the decimal. Now, the width specifier gives the TOTAL number of characters. (This is in line with the semantics of printf() in other languages.) See bugs #28633 and #29286 for more details.
Pacogliss 02-May-2005 12:08
Just a reminder for beginners : example 6 'printf("[%10s]\n",    $s);' only works (that is, shows out the spaces) if you put the html '<pre></pre>' tags ( head-scraping time saver ;-).
jrpozo at conclase dot net 21-Jan-2005 07:13
Be careful if you use the %f modifier to round decimal numbers as it (starting from 4.3.10) will no longer produce a float number if you set certain locales, so you can't accumulate the result. For example:

setlocale(LC_ALL, 'es_ES');
echo(sprintf("%.2f", 13.332) + sprintf("%.2f", 14.446))

gives 27 instead of 27.78, so use %F instead.
php at sharpdreams dot com 08-May-2004 02:13
Note that when using the argument swapping, you MUST number every argument, otherwise sprintf gets confused. This only happens if you use number arguments first, then switch to a non-numbered, and then back to a numbered one.

<?php
$sql = sprintf( "select * from %1\$s left join %2\$s on( %1\$s.id = %2\$s.midpoint ) where %1\$s.name like '%%%s%%' and %2\$s.tagname is not null", "table1", "table2", "bob" );
// Wont work:
// Sprintf will complain about not enough arguments.
$sql = sprintf( "select * from %1\$s left join %2\$s on( %1\$s.id = %2\$s.midpoint ) where %1\$s.name like '%%%3\$s%%' and %2\$s.tagname is not null", "table1", "table2", "bob" );
// Will work: note the %3\$s
?>
no dot email dot address at example dot com 16-Sep-2002 06:29
Using argument swapping in sprintf() with gettext: Let's say you've written the following script:

<?php
$var = sprintf(gettext("The %2\$s contains %1\$d monkeys"), 2, "cage");
?>

Now you run xgettext in order to generate a .po file. The .po file will then look like this:

#: file.php:9
#, ycp-format
msgid "The %2\\$s contains %1\\$d monkeys"
msgstr ""

Notice how an extra backslash has been added by xgettext.

Once you've translated the string, you must remove all backslashes from the ID string as well as the translation, so the po file will look like this:

#: file.php:9
#, ycp-format
msgid "The %2$s contains %1$d monkeys"
msgstr "Der er %1$d aber i %2$s"

Now run msgfmt to generate the .mo file, restart Apache to remove the gettext cache if necessary, and you're off.
abiltcliffe at bigfoot.com 10-Sep-2002 11:01
To jrust at rustyparts.com, note that if you're using a double-quoted string and *don't* escape the dollar sign with a backslash, $s and $d will be interpreted as variable references. The backslash isn't part of the format specifier itself but you do need to include it when you write the format string (unless you use single quotes).
Andrew dot Wright at spamsux dot atnf dot csiro dot au 03-Jul-2002 02:22
An error in my last example:
$b = sprintf("%30.s", $a);
will only add enough spaces before $a to pad the spaces + strlen($a) to 30 places.

My method of centering fixed text in a 72 character width space is:

$a = "Some string here";
$lwidth = 36; // 72/2
$b = sprintf("%".($lwidth + round(strlen($a)/2)).".s", $a);