Hướng dẫn text formatting php

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

sprintf — Return a formatted string

Description

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

Parameters

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.

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.

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:

Return Values

Returns a string produced according to the formatting string format.

Changelog

Examples

Example #1 Argument swapping

The format string supports argument numbering/swapping.

$num = 5;
$location = 'tree';$format = 'There are %d monkeys in the %s';
echo sprintf($format, $num, $location);
?>

The above example will output:

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:

$format = 'The %s contains %d monkeys';
echo sprintf($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:

$format = 'The %2$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.

$format = 'The %2$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

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

The above example will output:

Example #3 Position specifier with other specifiers

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

The above example will output:

The tree contains 0005 monkeys

Example #4 sprintf(): zero-padded integers

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

Example #5 sprintf(): formatting currency

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

The above example will output:

Example #6 sprintf(): scientific notation

$number = 362525200;

echo

The above example will output:

See Also

• printf() - Output a formatted string
• fprintf() - Write a formatted string to a stream
• vprintf() - Output a formatted string
• vsprintf() - Return a formatted string
• vfprintf() - Write a formatted string to a stream
• sscanf() - Parses input from a string according to a format
• fscanf() - Parses input from a file according to a format
• number_format() - Format a number with grouped thousands
• date() - Format a Unix timestamp

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

13 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:
printf('%%%s%%', 'koko'); #output: '%koko%'
?>

Alex R. Gibbs ¶

9 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:

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:

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  |

timo dot frenay at gmail dot com ¶

11 years ago

Here is how to print a floating point number with 16 significant digits regardless of magnitude:

    $result = sprintf(sprintf('%%.%dF', max(15 - floor(log10($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.

kontakt at myseosolution dot de ¶

7 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:
sprintf('%02d', 1);
?>

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

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

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

Output: 01.00

Please see http://stackoverflow.com/a/28739819/413531 for a more detailed explanation.

Anderson ¶

2 years ago

The old "monkey" example which helped me a lot has sadly disappeared.

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

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

// notice the double %%, this prints a literal '%' character

Nathan Alan ¶

5 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);

dwieeb at gmail dot com ¶

12 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 " " to achieve non-breaking space in strings returned by sprintf()

//Here is the function:
function sprintf_nbsp() {
   $args = func_get_args();
   return str_replace(' ', ' ', vsprintf(array_shift($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]!

//The variation that prints the string instead of returning it:
function printf_nbsp() {
   $args = func_get_args();
   echo str_replace(' ', ' ', vsprintf(array_shift($args), array_values($args)));
}
?>

Anonymous ¶

5 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);

viktor at textalk dot com ¶

13 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.

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
      $newargv = array(); // unhandled args in unchanged encodingwhile ($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 (

no dot email dot address at example dot com ¶

20 years ago

Using argument swapping in sprintf() with gettext: Let's say you've written the following script:

$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.

splogamurugan at gmail dot com ¶

13 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.

php at sharpdreams dot com ¶

18 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.

$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
?>

jfgrissom at gmail dot com ¶

13 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.

abiltcliffe at bigfoot.com ¶

20 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).

Pacogliss ¶

17 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 '

nate at frickenate dot com ¶

12 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).

/**
* 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

Hayley Watson ¶

10 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.

$pattern

john at jbwalker dot com ¶

8 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.

ian dot w dot davis at gmail dot com ¶

17 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.

php at mikeboers dot com ¶

13 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. =]

function sprintf_array($string, $array)
{
    $keys    = array_keys($array);
    $keysmap = array_flip($keys);
    $values  = array_values($array);

        while (

carmageddon at gmail dot com ¶

11 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:
$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.

hdimac at gmail dot com ¶

8 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.

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

11 years ago

Encoding and decoding IP adress to format: 1A2B3C4D (mysql column: char(8) )

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

jrpozo at conclase dot net ¶

17 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.

nmmm at nmmm dot nu ¶

7 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 "5"

geertdd at gmail dot com ¶

12 years ago

Note that when using a sign specifier, the number zero is considered positive and a "+" sign will be prepended to it.

printf('%+d', 0); // +0
?>

Astone ¶

13 years ago

When you're using Google translator, you have to 'escape' the 'conversion specifications' by putting around them.

Like this:

function getGoogleTranslation($sString, $bEscapeParams = true)
{
    // "escape" sprintf paramerters
    if ($bEscapeParams)
    {
        $sPatern = '/(?:%%|%(?:[0-9]+\$)?[+-]?(?:[ 0]|\'.)?-?[0-9]*(?:\.[0-9]+)?[bcdeufFosxX])/';       
        $sEscapeString = '$0';
        $sString = preg_replace($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>/';
        $sTranslation = preg_replace($sEscapePatern, '$1', $sTranslation);
    }// Return result
    return $sTranslation;
}?>

Thanks to MelTraX for defining the RegExp!

ignat dot scheglovskiy at gmail dot com ¶

9 years ago

Here is an example how alignment, padding and precision specifier can be used to print formatted list of items:

$out

scott dot gardner at mac dot com ¶

14 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);

John Walker ¶

13 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.

2838132019 at qq dot com ¶

1 year 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

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

20 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);

Anonymous ¶

6 months 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.

// 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);
?>

Sam Bull ¶

6 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));

Mirek Z... ¶

2 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;

ivan at php dot net ¶

8 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);