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substr_replace

(PHP 4, PHP 5)

substr_replace -- Replace text within a portion of a string

Description

mixed substr_replace ( mixed string, string replacement, int start [, int length] )

substr_replace() replaces a copy of string delimited by the start and (optionally) length parameters with the string given in replacement. The result string is returned. If string is an array then array is returned.

If start is positive, the replacing will begin at the start'th offset into string.

If start is negative, the replacing will begin at the start'th character from the end of string.

If length is given and is positive, it represents the length of the portion of string which is to be replaced. If it is negative, it represents the number of characters from the end of string at which to stop replacing. If it is not given, then it will default to strlen( string ); i.e. end the replacing at the end of string.

例子 1. substr_replace() example

<?php
$var = 'ABCDEFGH:/MNRPQR/';
echo "Original: $var<hr />\n";

/* These two examples replace all of $var with 'bob'. */
echo substr_replace($var, 'bob', 0) . "<br />\n";
echo substr_replace($var, 'bob', 0, strlen($var)) . "<br />\n";

/* Insert 'bob' right at the beginning of $var. */
echo substr_replace($var, 'bob', 0, 0) . "<br />\n";

/* These next two replace 'MNRPQR' in $var with 'bob'. */
echo substr_replace($var, 'bob', 10, -1) . "<br />\n";
echo substr_replace($var, 'bob', -7, -1) . "<br />\n";

/* Delete 'MNRPQR' from $var. */
echo substr_replace($var, '', 10, -1) . "<br />\n";
?>

注: 本函数可安全用于二进制对象。

See also str_replace() and substr().


add a note add a note User Contributed Notes
chuayw2000 at hotmail dot com
09-Dec-2005 07:33
I don't know if this function is multibyte safe but I've written a function that will do the same in multibyte mode.

<?php
//Check to see if it exists in case PHP has this function later
if (!function_exists("mb_substr_replace")){
   //Same parameters as substr_replace with the extra encoding parameter.
   function mb_substr_replace($string,$replacement,$start,$length=null,$encoding = null){
       if ($encoding == null){
           if ($length == null){
               return mb_substr($string,0,$start).$replacement;
           }
           else{
               return mb_substr($string,0,$start).$replacement.mb_substr($string,$start + $length);
           }
       }
       else{
           if ($length == null){
               return mb_substr($string,0,$start,$encoding).$replacement;
           }
           else{
               return mb_substr($string,0,$start,$encoding). $replacement. mb_substr($string,$start + $length,mb_strlen($string,$encoding),$encoding);
           }
       }
   }
}
?>
michael(at)webstaa(dot)com
06-Dec-2005 12:47
I created this because of the need to mask a credit-card number like **** **** **** 8862

string mask ( string str, int start [, int length] )

mask() masks a copy of str delimited by the start and (optionally) length parameters with asterisks (*) in place of non-whitespace characters

<?php
   function mask ( $str, $start = 0, $length = null ) {
       $mask = preg_replace ( "/\S/", "*", $str );
       if ( is_null ( $length )) {
           $mask = substr ( $mask, $start );
           $str = substr_replace ( $str, $mask, $start );
       } else {
           $mask = substr ( $mask, $start, $length );
           $str = substr_replace ( $str, $mask, $start, $length );
       }
       return $str;
   }
?>
hermes at andycostell dot com
28-Aug-2005 02:48
I suggest changing the function suggested by Guru Evi slightly. I found that it doesn't work as written here.

Original:
function add_3dots($string,$repl,$start,$limit) {
   if(strlen($string) > $limit) {
       return substr_replace(strip_tags($string),$repl,$start,$limit);
   } else {
       return $string;
   };
};

I suggest:
function add_3dots($string,$repl,$limit) {
       if(strlen($string) > $limit) {
           return substr_replace(strip_tags($string),$repl,$limit-strlen($repl));
       } else {
           return $string;
       }
   }

Usage:

$max_length=10;//the max number of characters you want to display
$too_long_string="BLAH BLAH BLAH BLAH BLAH etc.";//the string you want to shorten (if it's longer than the $limit)
$shorter_string=add_3_dots($too_long_string,"...",$max_length);
Guru Evi
13-Jul-2005 03:44
If your string is not long enough to meet what you specify in start and length then the replacement string is added towards the end of the string.

I wanted to replace the end of the string with ... if the string was too long to display (for instance article preview on a website). The problem was that my string was sometimes not that long and it still added the replacement string. So I wrote a function to replace substr_replace in my website:

function add_3dots($string,$repl,$start,$limit) {
   if(strlen($string) > $limit) {
       return substr_replace(strip_tags($string),$repl,$start,$limit);
   } else {
       return $string;
   };
};

I use strip_tags to strip out the HTML otherwise you might get a screwed up HTML (when a tags open in the string, but because you cut-off it doesn't)
ogt at parasane dot com
22-Jan-2005 07:02
Actually, just a minor correction to tekrat at 2d dot com's post:

Change the code....
<?
       if(strlen($substring) < 1){
           $string = $rep;
       }else{
           $string = $substring;
       }
?>

.... into....
<?
       if(strlen($substring) >= 1){
           $string = $substring;
       }
?>

.... otherwise you'll end up with the elipses (...) for any null strings.
tekrat at 2d dot com
07-Jan-2005 12:55
Here's a slightly revised version of the truncation function above.

Theres isn't much of a reason to  add in the $rep at the end of the original string is less then the truncation break point.
<?
   function truncate($substring, $max = 50, $rep = '...') {
       if(strlen($substring) < 1){
           $string = $rep;
       }else{
           $string = $substring;
       }
      
       $leave = $max - strlen ($rep);
      
       if(strlen($string) > $max){
           return substr_replace($string, $rep, $leave);
       }else{
           return $string;
       }
      
   }
?>
danieldoorduin at hotmail dot com
10-Dec-2004 06:48
Using substr_replace() can be avoided by using substr() instead:

<?
$string = substr($string, 0, $position_needle).$replace.substr($string, $position_needle+$length_needle);
?>

This can be useful when you need to replace parts of multibyte strings like strings encoded with utf-8. There isn't a multibute variant for substr_replace(), but for php substr() there is mb_substr(). For more information on multibyte strings see http://nl3.php.net/manual/en/ref.mbstring.php
titbits at nospam-4logical dot co dot uk
05-Aug-2004 05:28
A simple but useful 'pluralize' function using substr_replace:

  function pluralize($noun) {
   if ($noun{strlen($noun) -1} == "y")
     $noun = substr_replace($noun, "ies", strlen($noun) -1);
   else
     $noun .= "s";

   return $noun;
  }

Handy when displaying dynamic text.
dmron
18-Jun-2004 07:34
Regarding "...", even the short functions are too long and complicated, and there's no need to use substr_replace. substr() works better and is  way faster prior to 4.3.5 as the below poster stated.

function shorten( $str, $num = 100 ) {
  if( strlen( $str ) > $num ) $str = substr( $str, 0, $num ) . "...";
  return $str;
}
philip
14-May-2004 03:55
The substr_replace() function is extremely slow in PHP versions prior to 4.3.5 and 5.0.0 so consider using an alternative before this time.
tony at outshine dot com
10-May-2004 05:25
The comment by geniusdex is a good one.  Short, simple functions are the best.  But if the string is not longer than the limit set, NOTHING is returned.  Here is the function re-done to always return a string:

<?php
function dot($str, $len, $dots = "...") {
   if (strlen($str) > $len) {
       $dotlen = strlen($dots);
       $str = substr_replace($str, $dots, $len - $dotlen);
   }
   return $str;
}
?>
geniusdex ( at ) brz ( dot ) nu
23-Feb-2004 11:33
This is my version of making dotted strings:

<?php
function dot($str, $len, $dots = "...") {
   if (strlen($str) > $len) {
       $dotlen = strlen($dots);
       substr_replace($str, $dots, $len - $dotlen);
   }
}
?>
Thijs Wijnmaalen (thijs[at]nllinux.nl)
21-Jan-2004 03:05
I wrote a function that you can use for example in combination with a search script to cut off the articles that are too long.

<?php
function substr_index($text, $maxChars = 20, $splitter
= '...') {

$theReturn = $text;
$lastSpace = false;

if (strlen($text) > $maxChars) {
$theReturn = substr($text, 0, $maxChars - 1);

if (in_array(substr($text, $maxChars - 1, 1),
array(' ', '.', '!', '?'))) {
$theReturn .= substr($text, $maxChars, 1);
} else {
$theReturn = substr($theReturn, 0, $maxChars -
strlen($splitter));
$lastSpace = strrpos($theReturn, ' ');

if ($lastSpace !== false) {
$theReturn = substr($theReturn, 0, $lastSpace);
}

if (in_array(substr($theReturn, -1, 1), array(','))) {
$theReturn = substr($theReturn, 0, -1);
}
$theReturn .= $splitter;
}
}
return $theReturn;
}
?>
neon at lordneon dot com
05-Nov-2003 08:40
The easiest way (I think) to add trailing dots after a string which in my case are too long is:

<?
function dots($num, $string) {
   if (strlen($string) < $num) {
       $string = substr_replace($string, '...', '-10', $num);
   }
   return $string;
}

Then on your page do something like:
<? echo dots("30" $row['title']); ?>

if the string is greater than the specific number it'll replace 3 dots.

I hope this helps =)
?>
david at ethinkn dot com
06-Jul-2003 08:36
Here is a simple function to shorten a string and add an ellipsis

<?php

/**
 * truncate() Simple function to shorten a string and add an ellipsis
 *
 * @param string $string Origonal string
 * @param integer $max Maximum length
 * @param string $rep Replace with... (Default = '' - No elipsis -)
 * @return string
 * @author David Duong
 **/
function truncate ($string, $max = 50, $rep = '') {
   $leave = $max - strlen ($rep);
   return substr_replace($string, $rep, $leave);
}

echo truncate ('akfhslakdhglksjdgh', 10, '...');
// Returns akfhsla... (10 chrs)

?>
thomasNOSPAM at sportentranceNOSPAM dot com
09-Oct-2002 06:01
To abbreviate links into '...' if they outreach a certain amount of space; use the preg_replace function instead.

For instance you grabbed the headlines of a news site for use on your own page and the lines are to long:

asuming the raw material is stored in $unedited;

$edited = preg_replace("/(>)([[:print:]]{52,})(<)/e", "'\\1'.substr_replace('\\2 ', '...', '48').'\\3'", $unedited);
echo $edited;

This will shorten strings longer than 52 characters into 51 characters, with the last being three dots...
klaas at group94 dot com
14-Feb-2002 02:38
THE DOT DOT DOT ISSUE

PROBLEM:
You want to abbreviate a string.
E.g. You want "BritneySpears" to show as "BritneySpe...", being only the ten first characters followed by "..."

SOLUTION:
<?
$oRIGINAL = "BritneySpears";
$sHORTER = substr_replace($oRIGINAL, '...', 10);
echo ($sHORTER);
?>

This will result in BritneySpe...
29-Sep-2001 11:30
If you would like to remove characters from the start or end of a string, try the substr() function.

For example, to remove the last three characters from a string:
$string = "To be or not to be.";
$string = substr ($string, 0, -3);
mrbrown8 at juno dot com
17-Apr-2001 03:16
Just to add to the examples, if replacement is longer than length, only the length number of chars are removed from string and all of replacement is put in its place, and therefor strlen($string) is inreased.

$var = 'ABCDEFGH:/MNRPQR/';
/*  Should return ABCDEFGH:/testingRPQR/  */
echo substr_replace ($var, 'testing', 10, 2);
stefan at maifei dot com
02-Apr-2001 04:33
If you are trying to use -0, I don't think it works.  For example:

substr_replace($file,'',-4,0)

There may be an alternative though...
jgainey at infoave dot net
14-Mar-2001 10:29
[Editor's note: for a much simpler solution, use number_format()]

I had a situation in which I needed to add a comma to the third position of a number(the price of something).
<p>
$price = "12000";<br>
$price = substr_replace ($price, ',', -3, 0)";<br>
the result would be 12,000<p>
the -3 counts from right to left. a regular 3 would count from left to right
I hope this helps...
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