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PHP : Function Reference : String Functions : str_pad

str_pad

Pad a string to a certain length with another string (PHP 4 >= 4.0.1, PHP 5)
string str_pad ( string input, int pad_length [, string pad_string [, int pad_type]] )

Example 2444. str_pad() example

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<?php
$input = "Alien";
echo str_pad($input, 10);                      // produces "Alien     "
echo str_pad($input, 10, "-=", STR_PAD_LEFT);  // produces "-=-=-Alien"
echo str_pad($input, 10, "_", STR_PAD_BOTH);   // produces "__Alien___"
echo str_pad($input, 6 , "___");               // produces "Alien_"
?>

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Code Examples / Notes » str_pad

cd579
Why not just use a space[' '] instead of a character that COULD be inside the string, and risk messing it up?  Example:
$string = 'test';
$string = str_pad($string, 10, " ", STR_PAD_BOTH);
// $string now equals '      test'
$string = str_replace(" ", "&nbsp;", $string);

mreilly
When provided with a string of characters as the pad value, str_pad uses all the characters as fill, and can leave partial strings. (eg. If the pad value is 'ABC' and it needs 5 characters to pad with, it outputs 'ABCAB'.) This is a problem when you want to pad with non-breaking spaces, the code for which is 6 characters long.
This can be resolved by first padding the string with a single character that won't be found in the strings such as * then doing a str_replace of * with &nbsp;.

spudley
Warning: If your string includes non-ascii characters (eg the British pounds sign), str_pad() will treat these as two characters when calculating the padding.
So for example:
<?php
str_pad($currency_symbol.$showtottopay,12," ",STR_PAD_LEFT);
?>
will produce a different length string depending on whether $currency_symbol is pounds or dollars.
Hope this helps someone -- it caused me a lot of problems with misaligned columns in my invoices until I worked it out.

anloc
Tomek Krzeminski's iconv_str_pad modified for php 4 (iconv_strlen only works for php 5) courtesy of www.anloc.net
  function iconv_str_pad( $input, $pad_length, $pad_string = '', $pad_type = 1, $charset = "UTF-8" )
  {
      $str = '';
//       $length = $pad_length - iconv_strlen( $input, $charset );
       $length = $pad_length - preg_match_all('/./u', $input, $dummy);
      if( $length > 0)
      {
          if( $pad_type == STR_PAD_RIGHT )
          {
              $str = $input . str_repeat( $pad_string, $length );
          } elseif( $pad_type == STR_PAD_LEFT )
          {
              $str = str_repeat( $pad_string, $length ) . $input;
          } elseif( $pad_type == STR_PAD_BOTH )
          {
              $str = str_repeat( $pad_string, floor( $length / 2 ));
              $str .= $input;
              $str .= str_repeat( $pad_string, ceil( $length / 2 ));
          } else
          {
              $str = str_repeat( $pad_string, $length ) . $input;
          }
      } else
      {
          $str = $input;
      }
      return $str;
  }

rob
To reformat the date "3-3-2001" to "2001-03-03" you would use this regexp:
$newdate = preg_replace("/([0-9]+)-([0-9]+)-([0-9]+)/ie", "'\\3-'.str_pad('\\2', 2, '0', STR_PAD_LEFT).'-'.str_pad('\\1', 2, '0', STR_PAD_LEFT)", $date);

no_email
To convert your string couldnt you just use strval($var)?
What if you want non-breaking spaces? If I try to str_pad with "&nbsp;" PHP thinks my padding string is 6 characters, whn in HTML it is only one.

no dot spam
there could already be spaces in the string.
1) strlen the string
2) replace spaces with "AUniqueString"
3) strlen the new string
4) compare the two strlen's
5) pad as needed considering the new strlen
6) finally, replace all "AUniqueString" 's with &nbsp; 's
hack & a half, slow as well i bet

pozytron#mac#com
The trouble with cj@NOSPAM.ceejayoz.com's version over pestilenc@hotmail.com's is that many of the times it is used, it will end up with fragments of the "&nbsp;" code.
For example, the following code:
<?php
echo str_pad("TESTSTRING",60,"&nbsp;",STR_PAD_BOTH);
?>
produces the following HTML output:
&nbsp;&nbsp;&nbsp;&nbsp;&TESTSTRING&nbsp;&nbsp;&nbsp;&nbsp;&

giorgio dot balestrieri
str_pad vs. sprintf 2nd round :)
After to have seen Rex and Squeegee results, I've ran the code again, using different OSs and PHP version.
Here my results:
OpenBSD & PHP 4.3.4
str_pad test started, please wait...
str_pad cycle completed in 88 seconds
sprintf test started, please wait...
sprintf cycle completed in 69 seconds
Windows XP & PHP 5.0.0
str_pad test started, please wait...
str_pad cycle completed in 33 seconds
sprintf test started, please wait...
sprintf cycle completed in 27 seconds
RedHat Linux 7.3 & PHP 4.3.3
str_pad test started, please wait...
str_pad cycle completed in 63 seconds
sprintf test started, please wait...
sprintf cycle completed in 43 seconds
sprintf seem to be faster yet, but considering Rex and Squeegee test, this cannot be considered always true... somebody want try more? Only to understand why... :)

michal nazarewicz, min86
Re ks:
Your function does something different if $padchar is not a chararcter but rather a string. Still, however, private's function may be simplified:
<?php
function str_pad_right($str, $pad, $len) {
   return $str . str_pad('', $len, $pad);
}
function str_pad_left($str, $pad, $len) {
   return str_pad('', $len, $pad) . $str;
}
function str_pad_both($str, $pad, $len) {
   return ($s = str_pad('', $len, $pad)) . $str . $s;
}
?>

david dot rensonnet
my solution to saveloywill at netscape dot net:
$myvar2="Alien";
$myvar=str_pad($myvar2,15," ",STR_PAD_RIGHT);
$myvar=str_replace(" ","&nbsp;",$myvar);
this way, only complete spaces will show up.
enjoy!
david rensonnet

charles
More corrections to the original flap / Tomek Krzeminski code below (well someone has to check it!) -- the code is a bit mangled but it is still the same:
<?php
function mb_str_pad($ps_input, $pn_pad_length, $ps_pad_string = " ", $pn_pad_type = STR_PAD_RIGHT, $ps_encoding = NULL) {
 $ret = "";
 if (is_null($ps_encoding))
   $ps_encoding = mb_internal_encoding();
 $hn_length_of_padding = $pn_pad_length - mb_strlen($ps_input, $ps_encoding);
 $hn_psLength = mb_strlen($ps_pad_string, $ps_encoding); // pad string length
 
 if ($hn_psLength <= 0 || $hn_length_of_padding <= 0) {
   // Padding string equal to 0:
   //
   $ret = $ps_input;
   }
 else {
   $hn_repeatCount = floor($hn_length_of_padding / $hn_psLength); // how many times repeat
   if ($pn_pad_type == STR_PAD_BOTH) {
     $hs_lastStrLeft = "";
     $hs_lastStrRight = "";
     $hn_repeatCountLeft = $hn_repeatCountRight = ($hn_repeatCount - $hn_repeatCount % 2) / 2;
     $hs_lastStrLength = $hn_length_of_padding - 2 * $hn_repeatCountLeft * $hn_psLength; // the rest length to pad
     $hs_lastStrLeftLength = $hs_lastStrRightLength = floor($hs_lastStrLength / 2);      // the rest length divide to 2 parts
     $hs_lastStrRightLength += $hs_lastStrLength % 2; // the last char add to right side
     $hs_lastStrLeft = mb_substr($ps_pad_string, 0, $hs_lastStrLeftLength, $ps_encoding);
     $hs_lastStrRight = mb_substr($ps_pad_string, 0, $hs_lastStrRightLength, $ps_encoding);
     $ret = str_repeat($ps_pad_string, $hn_repeatCountLeft) . $hs_lastStrLeft;
     $ret .= $ps_input;
     $ret .= str_repeat($ps_pad_string, $hn_repeatCountRight) . $hs_lastStrRight;
     }
   else {
     $hs_lastStr = mb_substr($ps_pad_string, 0, $hn_length_of_padding % $hn_psLength, $ps_encoding); // last part of pad string
     if ($pn_pad_type == STR_PAD_LEFT)
       $ret = str_repeat($ps_pad_string, $hn_repeatCount) . $hs_lastStr . $ps_input;
     else
       $ret = $ps_input . str_repeat($ps_pad_string, $hn_repeatCount) . $hs_lastStr;
     }
   }
 return $ret;
 }
?>

jared
matthew.somerville's code did NOT work for me.
neither did bert@catsburg.com's.
neither did any other documentation.
(if I isolated the code by itself, they all worked; but in the context I was using it, $value was numeric, and there is NO WAY to force it to be a string in PHP).
I had to roll my own. I used 'trim' to _force_
the value of $value to be string, because as
long as PHP thought it was numeric, I could
not use any form of left-padding with zeros.
This worked (I use sprintf to left-pad
$value with zeros to a length of 4):
sprintf("%04s",trim($value));

rafaeljaquestudojunto
Looking forward to make some dynamic tabulation, i've noticed that the output appeared twice. I suppose that the parser recognize \t, \n and any other special character as a single character...
So.. If you need 4 tabulatins, just make...
<?php
print str_pad('',4,"\t");
?>

ks
in reply to private dot email at optusnet dot com dot au:
you are defying the point of padding by adding a fixed amount of characters!
anyways, your functions are equivalent to the much simpler form of e.g.:
<?php
function str_pad_right($string, $padchar, $int) {
  return $str . str_repeat($padchar, $int);
}
?>

bob
In a lot of cases you're better off using str_repeat if you want to use something like   - it repeats the entire string.
Using str_repeat, I wrote a full string pad function that should closely mimic str_pad in every other way:
<?php
function full_str_pad($input, $pad_length, $pad_string = '', $pad_type = 0) {
$str = '';
$length = $pad_length - strlen($input);
if ($length > 0) { // str_repeat doesn't like negatives
 if ($pad_type == STR_PAD_RIGHT) { // STR_PAD_RIGHT == 1
  $str = $input.str_repeat($pad_string, $length);
 } elseif ($pad_type == STR_PAD_BOTH) { // STR_PAD_BOTH == 2
  $str = str_repeat($pad_string, floor($length/2));
  $str .= $input;
  $str .= str_repeat($pad_string, ceil($length/2));
 } else { // defaults to STR_PAD_LEFT == 0
  $str = str_repeat($pad_string, $length).$input;
 }
} else { // if $length is negative or zero we don't need to do anything
 $str = $input;
}
return $str;
}
$pad_me = "Test String";
echo '|'.full_str_pad($pad_me, 20, ' ')."|\n";
echo '|'.full_str_pad($pad_me, 20, ' ', STR_PAD_RIGHT)."|\n";
echo '|'.full_str_pad($pad_me, 20, ' ', STR_PAD_BOTH)."|\n";
?>

tacomage
If you want to pad a string to a certain screen length with &nbsp; or other HTML entities, but don't want to risk messing up any HTML characters inside the string, try this:
<?
function str_pad_as_single($input, $len, $pad, $flag=STR_PAD_RIGHT)
{
 $trans=array('$'=>$input,' '=>$pad);
 $output=str_pad('$',$len-strlen($input)+1,' ',$flag);
 $output=strtr($output,$trans);
 return $output;
}
echo str_pad_as_single('<img src="some.gif">',22,'&nbsp;');
// will output <img src="some.gif">&nbsp;&nbsp;
echo str_pad_as_single('<img src="some.gif">',22,'&nbsp;',STR_PAD_BOTH);
// will output &nbsp;<img src="some.gif">&nbsp;
echo str_pad_as_single('<img src="some.gif">',22,'&nbsp;',STR_PAD_LEFT);
// will output &nbsp;&nbsp;<img src="some.gif">
?>
It works by using single characters for str_pad, then replacing the characters with the full strings using strtr, so the two strings can't interfere with each other.  It also conveniently has the same syntax as str_pad.  Yes, I realize that spacing an image with text isn't the best idea, but it's just an example, it'll apply to other HTML as well :-P

private dot email
I wrote these 3 functions that live in a library i include in every programme. I find them useful, and the syntax is easy.
<?php
$str = "test";
function str_pad_right ( $string , $padchar , $int ) {
$i = strlen ( $string ) + $int;
$str = str_pad ( $string , $i , $padchar , STR_PAD_RIGHT );
return $str;
}

function str_pad_left ( $string , $padchar , $int ) {
$i = strlen ( $string ) + $int;
$str = str_pad ( $string , $i , $padchar , STR_PAD_LEFT );
return $str;
}

function str_pad_both ( $string , $padchar , $int ) {
$i = strlen ( $string ) + ( $int * 2 );
$str = str_pad ( $string , $i , $padchar , STR_PAD_BOTH );
return $str;
}
echo str_pad_left ( $str , "-" , 3 ); // Produces: ---test
echo str_pad_right ( $str , "-" , 3 ); // Produces: test---
echo str_pad_both ( $str , "-" , 3 ); // Produces: ---test---
?>
Hope this can help someone!

tharkos
I think the simply way to print the special HTML character &nbsp; as string is usin the conversion types.
La manera más simple de utilizar el caracter especial de HTML &nbsp; como un string es usando la comversión de tipos
echo str_repeat("&nbsp".chr(59), 10)

02-nov-2004 01:15
I just looked at bob[at]bobarmadillo[dot]coms version of str_pad and notice that he dint take into account the length of the padded string. He's assumed this is a single character, which the examples show it to be a string of characters.

matthew dot somerville
I find:
$mystr = substr("0000$mystr",-4)
(where the 0s are padding characters and -4 is the negative of the maxlength to pad to) is even simpler.

flap
here is some extension to Tomek Krzeminski example. It works correctly when length of pad_string is greater than 1
(orig by Tomek Krzeminski)
function m_str_pad($input, $pad_length, $pad_string = '', $pad_type = 1, $charset = null){
$str = '';
     
if ($charset==null)
$charset = mb_internal_encoding();
     
$length = $pad_length - mb_strlen($input, $charset);

$psLength = mb_strlen($pad_string); // pad string length

if ($psLength<=0 OR $length<=0){
// pad string equal 0
$str = $input;
}else{
// pad string AND space to padding is greater than 1
$repeatCount = floor($length/$psLength); // how many times repeat
$lastStr = substr($pad_string, 0, $length%$psLength); // last part of pad string

if($pad_type == STR_PAD_RIGHT){
$str = $input.str_repeat($pad_string, $repeatCount).$lastStr;
} elseif($pad_type == STR_PAD_LEFT){
$str = str_repeat($pad_string, $repeatCount).$lastStr.$input;
} elseif($pad_type == STR_PAD_BOTH){
$repeatCountLeft = 0;
$repeatCountRight = 0;
$lastStrLeft = '';
$lastStrRight = '';

if ($repeatCount%2==0){
// if is divisible 2
$repeatCountLeft = $repeatCountRight = floor($repeatCount/2);
}else{
// if not - has to dive to 2 same parts
$repeatCountLeft = $repeatCountRight = floor(($repeatCount-1)/2);
}

$lastStrLength = $length-2*$repeatCountLeft*$psLength; // the rest length to pad
$lastStrLeftLength = $lastStrRightLength = floor($lastStrLength/2); // ther rest length divide to 2 parts
$lastStrRightLength += $lastStrLength%2; // the last char add to right side

$lastStrLeft = substr($pad_string, 0, $lastStrLeftLength);
$lastStrRight = substr($pad_string, 0, $lastStrRightLength);

$str  = str_repeat($pad_string,$repeatCountLeft).$lastStrLeft;
$str .= $input;
$str .= str_repeat($pad_string,$repeatCountRight).$lastStrRight;
} else{
$str = str_repeat($pad_string, $repeatCount).$lastStr.$input;
}
}
     
return $str;
}

saveloywill
Here is my solution to the above problem.
Simply place the code in question inbetween  html <pre> tags, like this:
<?php
print "<pre>";
$input = "Alien";
print str_pad($input, 10);
print "*";
print "</pre>";
?>
Thanks.

silvio ginter silvio dot ginter
Hello,
i updated the function in my last post. it should be much more performant now.
<?php
$string = 'this is a test';
$oldLen = strlen($string);
$direction = STR_PAD_BOTH;
echo $string.'
';
echo str_const_len($string, 101, '#', $direction).'
';
echo $string.'
';
echo str_const_len($string, $oldLen, '#', $direction).'
';
echo $string.'
'."\n";


/* This function is an extension to str_pad, it manipulates the referenced
string '$str' and stretches or reduces it to the specified length. It
returns the number of characters, that were added or stripped. */
function str_const_len(&$str, $len, $char = ' ', $str_pad_const = STR_PAD_RIGHT) {
$origLen = strlen($str);
if (strlen($str) < $len) { /* stretch string */
$str = str_pad($str, $len, $char, $str_pad_const);
}
else { /* reduce string */
switch ($str_pad_const) {
case STR_PAD_LEFT:
$str = substr($str, (strlen($str) - $len), $len);
break;
case STR_PAD_BOTH:
$shorten = (int) ((strlen($str) - $len) / 2);
$str = substr($str, $shorten, $len);
break;
default:
$str = substr($str, 0, $len);
break;
}
}
return ($len - $origLen);
}
?>

tomek krzeminski
for those who want to pad strings in UTF-8 charset (for example)
(orig by bob)
---------------
private function iconv_str_pad( $input, $pad_length, $pad_string = '', $pad_type = 1, $charset = "UTF-8" )
{
$str = '';
$length = $pad_length - iconv_strlen( $input, $charset );

if( $length > 0)
{
if( $pad_type == STR_PAD_RIGHT )
{
$str = $input . str_repeat( $pad_string, $length );
} elseif( $pad_type == STR_PAD_LEFT )
{
$str = str_repeat( $pad_string, $length ) . $input;
} elseif( $pad_type == STR_PAD_BOTH )
{
$str = str_repeat( $pad_string, floor( $length / 2 ));
$str .= $input;
$str .= str_repeat( $pad_string, ceil( $length / 2 ));
} else
{
$str = str_repeat( $pad_string, $length ) . $input;
}
} else
{
$str = $input;
}

return $str;
}

giorgio dot balestrieri
For number formatting (like writing numbers with leading zeroes etc.) , sprintf is much faster than str_pad.
Consider the following snippet (it take some minutes to run):
<?
 echo "str_pad test started, please wait...\n";
 
 $intStart = time();
 for ($idx = 1; $idx <= 10000000; $idx++)
   $strFoo = str_pad($idx, 10, "0", STR_PAD_LEFT);
 $intEnd = time();
 
 echo "str_pad cycle completed in " . ($intEnd - $intStart) . " seconds\n";
 echo "sprintf test started, please wait...\n";  
 
 $intStart = time();
 for ($idx = 1; $idx <= 10000000; $idx++)
   $strFoo = sprintf("%010d", $idx);
 $intEnd = time();
 
 echo "sprintf cycle completed in " . ($intEnd - $intStart) . " seconds\n";
?>
The str_pad cyle runs 80-100% slower on my pc...

pestilenc
For me this worked.
$string = 'help';
#First, str_pad() with unique character.
$string = str_pad($string, 10, "*", STR_PAD_BOTH);
#$string = '***help***';
#Second, str_replace with '&nbsp;'
$string = str_replace("*", "&nbsp;", $string);

christian dot reinecke
Fills the first argument (mostly a number, f.e. from a <select> loop to display a date or time) with zeroes.
<?php
function zerofill($mStretch, $iLength = 2)
{
   $sPrintfString = '%0' . (int)$iLength . 's';
   return sprintf($sPrintfString, $mStretch);
}
?>
sprintf() is indeed faster than str_pad.

ed
Combining it into a handy one liner could be:
$string = str_replace(" ", "&nbsp;", str_pad($string, 10, " ", STR_PAD_BOTH));

fahad dot gilani
Basically, *all* of you guys have a 'long' way of padding text with html tags (which includes &nbsp;) You dont even have to do a str_replace... try the following code and this will work with ANY html tag there is out there and you don't have to worry about tag character lengths so on and so forth:
<?
 $text = "This is pretty interesting!";
 $pad_string = "&nbsp;";
 
 //Pad text on both sides
 $text = str_pad($text, strlen($text)+(20*strlen($pad_string)), $pad_string, STR_PAD_BOTH);
 print $text." Dont you think?";
?>
Will produce:
         This is pretty interesting!           Dont you think?
Cheers,
Fahad

cj
Another solution to no_email@php.net's problem would be to simply multiply the padding string by 6.
e.g.
$string = str_pad($string, 10, "&nbsp;", STR_PAD_BOTH);
becomes
$string = str_pad($string, 60, "&nbsp;", STR_PAD_BOTH);
which will avoid problems with the above solution, which will mess up text that has the * in it (or whichever character you're replacing)

anon
alternatively use substr_replace to zero pad:
   $new_id = substr_replace("00000", $id, -1 * strlen($id));

zubfatal
<?php
/**
* str_pad_html - Pad a string to a certain length with another string.
* accepts HTML code in param: $strPadString.
*
* @name str_pad_html()
* @author Tim Johannessen <root@it.dk>
* @version 1.0.0
* @param string $strInput The array to iterate through, all non-numeric values will be skipped.
* @param int $intPadLength Padding length, must be greater than zero.
* @param string [$strPadString] String to pad $strInput with (default: &nbsp;)
* @param int [$intPadType] STR_PAD_LEFT, STR_PAD_RIGHT (default), STR_PAD_BOTH
* @return string Returns the padded string
**/
function str_pad_html($strInput = "", $intPadLength, $strPadString = "&nbsp;", $intPadType = STR_PAD_RIGHT) {
if (strlen(trim(strip_tags($strInput))) < intval($intPadLength)) {

switch ($intPadType) {
// STR_PAD_LEFT
case 0:
$offsetLeft = intval($intPadLength - strlen(trim(strip_tags($strInput))));
$offsetRight = 0;
break;

// STR_PAD_RIGHT
case 1:
$offsetLeft = 0;
$offsetRight = intval($intPadLength - strlen(trim(strip_tags($strInput))));
break;

// STR_PAD_BOTH
case 2:
$offsetLeft = intval(($intPadLength - strlen(trim(strip_tags($strInput)))) / 2);
$offsetRight = round(($intPadLength - strlen(trim(strip_tags($strInput)))) / 2, 0);
break;

// STR_PAD_RIGHT
default:
$offsetLeft = 0;
$offsetRight = intval($intPadLength - strlen(trim(strip_tags($strInput))));
break;
}

$strPadded = str_repeat($strPadString, $offsetLeft) . $strInput . str_repeat($strPadString, $offsetRight);
unset($strInput, $offsetLeft, $offsetRight);

return $strPadded;
}

else {
return $strInput;
}
}
?>

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vfprintf
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