sprintf

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

sprintf — Restituisce una stringa formattata

Descrizione

sprintf(string $format, mixed $args = ?, mixed $... = ?): string

La funzione restituisce una stringa formattata in base al parametro format.

La stringa di formato è composta da 0 o più direttive: i caratteri ordinari (escluso il %) sono copiati direttamente nel risultato, mentre le specifiche di conversione, scaricano il proprio parametro. Queste note si applicano alle funzioni fprintf(), sprintf() e printf().

Ciascun parametro di conversione consiste nel segno percento (%), seguito da uno più dei seguenti elementi nell'ordine si ha:

Un parametro opzionale di specifica del segno che forza la presenza del segno (- oppure +) in caso di numero. Per default, si usa soltanto il segno - se il numero è negativo. Questo parametro forza i numeri positiva ad avere il segno +, ed è stato aggiunto in PHP 4.3.0.
Un parametro opzionale per la specifica del riempimento che indica quale carattere sarà utilizzato per completare la stringa risultante in modo da raggiungere la dimensione richiesta. Questo può essere uno spazio oppure uno 0 (il carattere zero). Per default si completa con spazi. Un carattere di riempimento alternativo può essere indicato anteponendo a questo l'apice singolo ('). Vedere gli esempi seguenti.
Un parametro opzionale per la specifica dell'allineamento che indica se la stringa risultante debba essere giustificata a destra o a sinistra. Per default le stringhe sono giustificate a destra; il carattere - forza la giustificazione a sinistra.
Un parametro numerico opzionale per la specifica della dimensione che indica di quanti caratteri (come minimo) debba essere lunga la stringa.
Un parametro opzionale per indicare la precisione per indicare quante cifre decimali debbano essere visualizzate per i numeri in virgola mobile. Quando si usa questo parametro in una stringa si impone come una sorta di punto di cutoff, esso imposta un limite alla lunghezza della stringa.
Una specifica di tipo che indica il tipo di dati dell'argomento. I possibili tipi sono:
- % - il carattere percento. Nessun argomento è richiesto.
- b - l'argomento è trattato come un intero e sarà presentato come numero binario.
- c - l'argomento è trattato come un intero e sarà presentato come carattere ASCII del valore corrispondente.
- d - l'argomento è trattato come un intero e sarà presentato come un numero decimale con segno.
- e - l'argomento è reso con notazione scientifica (ad esempio 1.2e+2).
- u - l'argomento è trattato come un intero e sarà presentato come un numero decimale senza segno.
- f - l'argomento è trattato come un float e sarà presentato come un numero in virgola mobile (influenzato dalle impostazioni locali).
- F - l'argomento è trattato come un numero float, e sarà presentato come un numero in virgola mobile (non influenzato dalle impostazioni locali). Disponibile da PHP 4.3.10 e PHP 5.0.3.
- o - l'argomento è trattato come un intero e sarà presentato come un numero ottale.
- s - l'argomento sarà trattato e presentato come una stringa.
- x - l'argomento sarà trattato come un intero e presentato in forma esadecimale (con le lettere in minuscolo).
- X - l'argomento è trattato come un intero e sarà presentato come un numero esadecimale (con le lettere maiuscole).

A partire dal PHP 4.0.6 la stringa di formato supporta lo scambio dei parametri. Eccone un esempio:

Example #1 Scambio dei parametri

<?php
$format = "There are %d monkeys in the %s";
printf($format, $num, $location);
?>

Questo esempio visualizza: "There are 5 monkeys in the tree". Ma supponiamo di volere creare una stringa di formato in file a parte, perché vogliamo rendere la procedura internazionale; e pertanto riscriviamo l'esempio come:

Example #2 Scambio dei parametri

<?php
$format = "The %s contains %d monkeys";
printf($format, $num, $location);
?>

Ora abbiamo un problema. L'ordine dei segnaposto nella stringa di formato non coincide con l'ordine dei parametri. Si vorrebbe potere lasciare inalterato il codice e potere indicare a quale parametro si riferisce il segnaposto. Ciò può essere fatto modificando la stringa di formato come:

Example #3 Scambio dei parametri

<?php
$format = "The %2\$s contains %1\$d monkeys";
printf($format, $num, $location);
?>

Un beneficio aggiuntivo è che si possono ripetere i segnaposto senza dovere ripetere i parametri. Ad esempio:

Example #4 Scambio di parametri

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

Vedere anche printf(), sscanf(), fscanf(), vsprintf() e number_format().

Esempi

Example #5 Esempi di uso di printf()

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

// attenzione che i doppi %%, visualizzano il carattere '%' 
printf("%%b = '%b'\n", $n); // rappresentazione binaria
printf("%%c = '%c'\n", $c); // visualizza un carattere ASCII, coma la funzione chr()
printf("%%d = '%d'\n", $n); // rappresentazione di un intero standard
printf("%%e = '%e'\n", $n); // notazione scientifica
printf("%%u = '%u'\n", $n); // rappresentazione di un intero positivo privo di segno
printf("%%u = '%u'\n", $u); // rappresentazione di un intero negativo privo di segno
printf("%%f = '%f'\n", $n); // rappresentazine in virgola mobile
printf("%%o = '%o'\n", $n); // rappresentazione ottale
printf("%%s = '%s'\n", $n); // stringa
printf("%%x = '%x'\n", $n); // rappresentazione esadecimale (minuscolo)
printf("%%X = '%X'\n", $n); // rappresentazione esadecimale (maiuscolo)
printf("%%+d = '%+d'\n", $n); // indicazione del segno su un intero positivo
printf("%%+d = '%+d'\n", $u); // indicazione del segno su un intero negativo
?>

L'output di questo programma sarà:

%b = '10100111101010011010101101'
%c = 'A'
%d = '43951789'
%e = '4.39518e+7'
%u = '43951789'
%u = '4251015507'
%f = '43951789.000000'
%o = '247523255'
%s = '43951789'
%x = '29ea6ad'
%X = '29EA6AD'
%+d = '+43951789'
%+d = '-43951789'

Example #6 printf(): specifiche di stringa

<?php
$s = 'monkey';
$t = 'many monkeys';

printf("[%s]\n",      $s); // output standard di stringa
printf("[%10s]\n",    $s); // accostamento a destra con spazi
printf("[%-10s]\n",   $s); // accostamento a sinistra con spazi
printf("[%010s]\n",   $s); // completamento con zero funziona anche con le stringhe
printf("[%'#10s]\n",  $s); // utilizza il carattere di riempimento  '#'
printf("[%10.10s]\n", $t); // accostamento a sinistra con taglio a 10 caratteri
?>

L'output di questo programma sarà:

[monkey]
[    monkey]
[monkey    ]
[0000monkey]
[####monkey]
[many monke]

Example #7 sprintf(): interi completati con zeri

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

Example #8 sprintf(): formattazione della moneta

<?php
$money1 = 68.75;
$money2 = 54.35;
$money = $money1 + $money2;
// echo $money visualizzerà "123.1";
$formatted = sprintf("%01.2f", $money);
// echo $formatted visualizzerà "123.10"
?>

Example #9 sprintf(): notazione scientifica

<?php
$number = 362525200;

echo sprintf("%.3e", $number); // visualizza 3.63e+8
?>

add a note

User Contributed Notes 36 notes

down

103

remy dot damour at -please-no-spam-laposte dot net ¶

15 years ago


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%'
?>

down

Alex R. Gibbs ¶

11 years ago


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  |

down

timo dot frenay at gmail dot com ¶

13 years ago


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.

down

kontakt at myseosolution dot de ¶

9 years ago


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.

down

nate at frickenate dot com ¶

15 years ago


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));
}

?>

down

Anonymous ¶

7 years ago


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);

down

jfgrissom at gmail dot com ¶

15 years ago


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.

down

ian dot w dot davis at gmail dot com ¶

19 years ago


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.

down

Anderson ¶

5 years ago


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]
*/
?>

down

viktor at textalk dot com ¶

15 years ago


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);
  }
}
?>

down

dwieeb at gmail dot com ¶

14 years ago


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)));
}
?>

down

abiltcliffe at bigfoot.com ¶

22 years ago


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).

down

carmageddon at gmail dot com ¶

13 years ago


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.

down

Pacogliss ¶

19 years ago


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 ;-).

down

no dot email dot address at example dot com ¶

22 years ago


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.

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Hayley Watson ¶

12 years ago


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");
?>

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splogamurugan at gmail dot com ¶

15 years ago


$format = 'There are %1$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.

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php at mikeboers dot com ¶

16 years ago


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!

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krzysiek dot 333 at gmail dot com - zryty dot hekko dot pl ¶

13 years ago


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]);
}
?>

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john at jbwalker dot com ¶

10 years ago


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.

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php at sharpdreams dot com ¶

20 years ago


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
?>

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geertdd at gmail dot com ¶

14 years ago


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
?>

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Nathan Alan ¶

7 years ago


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);

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ignat dot scheglovskiy at gmail dot com ¶

12 years ago


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 
?>

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jrpozo at conclase dot net ¶

19 years ago


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.

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hdimac at gmail dot com ¶

10 years ago


In the examples, is being shown printf, but it should say sprintf, which is the function being explained... just a simple edition mistake.

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nmmm at nmmm dot nu ¶

9 years ago


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"

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scott dot gardner at mac dot com ¶

16 years ago


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);

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John Walker ¶

15 years ago


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.

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Anonymous ¶

2 years ago


If the format string is enclosed in double-quotes (""), you need to escape the dollar sign after argnum with a backslash character (\), like this %1\$s, so that the PHP doesn't try to interpret them as variable. Using a backslash like this is called an escape sequence.

<?php
// Sample string
$number = 499;
$format = "The number without decimal points: %1\$d, and the number with two decimal points: %1\$.2f";

// Formatting and print the string
printf($format, $number);
?>

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Andrew dot Wright at spamsux dot atnf dot csiro dot au ¶

22 years ago


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);

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ivan at php dot net ¶

10 years ago


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);

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Astone ¶

15 years ago


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!

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-1

Sam Bull ¶

9 years ago


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));

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-3

Mirek Z... ¶

4 years ago


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;

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-4

2838132019 at qq dot com ¶

3 years ago


echo sprintf("%.2f", "123456789012345.82");  
// result: 123456789012345.81

echo sprintf("%.2f", "123456789012345.85");
// result: 123456789012345.84

echo sprintf("%.2f", "123456789012345.87");
//result:  123456789012345.88

echo sprintf("%.2f", "123456789012345.820"); 
//result: 123456789012345.81

echo sprintf("%.2f", "123456789012345.821");  
//result: 123456789012345.83

echo sprintf("%.2f", "123456789012345.828");  
//result: 123456789012345.83

echo sprintf("%.2f", "123456789012345.8209"); 
//result : 123456789012345.83

echo sprintf("%.2f", "1234567890123456.82"); 
//result: 1234567890123456.75

echo sprintf("%.2f", "123456789012345.82002"); 
//result: 123456789012345.81

echo sprintf("%.2f", "123456789012345.820001"); 
//result: 123456789012345.81

echo sprintf("%.2f", "123456789012345.820101");
//result: 123456789012345.81

echo sprintf("%.2f", "123456789012345.820201");
//result: 123456789012345.81

echo sprintf("%.2f", "123456789012345.820301");
//result: 123456789012345.81

echo sprintf("%.2f", "123456789012345.820401");
//result: 123456789012345.83

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