字符串 函数
PHP Manual

substr_replace

(PHP 4, PHP 5, PHP 7)

substr_replace替换字符串的子串

说明

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

substr_replace() 在字符串 string 的副本中将由 start 和可选的 length 参数限定的子字符串使用 replacement 进行替换。

参数

string

输入字符串。

An array of strings can be provided, in which case the replacements will occur on each string in turn. In this case, the replacement, start and length parameters may be provided either as scalar values to be applied to each input string in turn, or as arrays, in which case the corresponding array element will be used for each input string.

replacement

替换字符串。

start

如果 start 为正数,替换将从 stringstart 位置开始。

如果 start 为负数,替换将从 string 的倒数第 start 个位置开始。

length

如果设定了这个参数并且为正数,表示 string 中被替换的子字符串的长度。如果设定为负数,它表示待替换的子字符串结尾处距离 string 末端的字符个数。如果没有提供此参数,那么它默认为 strlen( string ) (字符串的长度)。当然,如果 length 为 0,那么这个函数的功能为将 replacement 插入到 stringstart 位置处。

返回值

返回结果字符串。如果 string 是个数组,那么也将返回一个数组。

更新日志

版本 说明
4.3.3 All parameters now accept arrays.

范例

Example #1 substr_replace() 范例

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

/* 这两个例子使用 "bob" 替换整个 $var。*/
echo substr_replace($var'bob'0) . "<br />\n";
echo 
substr_replace($var'bob'0strlen($var)) . "<br />\n";

/* 将 "bob" 插入到 $var 的开头处。*/
echo substr_replace($var'bob'00) . "<br />\n";

/* 下面两个例子使用 "bob" 替换 $var 中的 "MNRPQR"。*/
echo substr_replace($var'bob'10, -1) . "<br />\n";
echo 
substr_replace($var'bob', -7, -1) . "<br />\n";

/* 从 $var 中删除 "MNRPQR"。*/
echo substr_replace($var''10, -1) . "<br />\n";
?>

Example #2 Using substr_replace() to replace multiple strings at once

<?php
$input 
= array('A: XXX''B: XXX''C: XXX');

// A simple case: replace XXX in each string with YYY.
echo implode('; 'substr_replace($input'YYY'33))."\n";

// A more complicated case where each replacement is different.
$replace = array('AAA''BBB''CCC');
echo 
implode('; 'substr_replace($input$replace33))."\n";

// Replace a different number of characters each time.
$length = array(123);
echo 
implode('; 'substr_replace($input$replace3$length))."\n";
?>

以上例程会输出:

A: YYY; B: YYY; C: YYY
A: AAA; B: BBB; C: CCC
A: AAAXX; B: BBBX; C: CCC

注释

Note: 此函数可安全用于二进制对象。

参见

User Contributed Notes

nospam at nospam dot com 22-Jan-2016 06:45
<?php

// shortens a long string to a max length while inserting a string into the exact middle
function strShorten($str, $maxlen = 10, $insert = '/.../') {
  if (
$str && !is_array($str)) { // valid string
   
if ($maxlen && is_numeric($maxlen) && $maxlen < strlen($str)) { // string needs shortening
     
if ($insert && ($ilen = strlen($insert))) { // insert string and length
       
if ($ilen >= $maxlen) { // insert string too long so use default insert
         
$insert = '**'; // short default so works even when a very small $maxlen
         
$ilen = 2;
        }
      }
     
$chars = $maxlen - $ilen; // number of $str chars to keep
     
$start = ceil($chars/2); // position to start cutting
     
$end = floor($chars/2); // position from end to stop cutting
     
return substr_replace($str, $insert, $start, -$end); // first.insert.last
   
} else { // string already short enough
     
return $str; // return original string
   
}
  }
}

echo
strShorten('123456789', 6, ''); // outputs 123789
echo strShorten('123456789', 6, '-'); // outputs 123-89
echo strShorten('123456789', 6, 'longstring'); // outputs 12**89
echo strShorten('abcdefghijklmnopqrstuvwxyz', 10, '..'); // outputs abcd..wxyz
echo strShorten('abcdefghijklmnopqrstuvwxyz'); // outputs abc/.../yz

?>
olav at schettler dot net 02-Nov-2015 05:12
Please note that the function array_slice(), which has a similar functionality but for arrays rather than for strings, has its parameters in a different order.
ivijan dot stefan at gmail dot com 06-Mar-2014 05:15
I have a little function that works like substr_replace ()  what I use for some purpose. Maybe someone needs it.

<?php
function putinplace($string=NULL, $put=NULL, $position=false)
{
   
$d1=$d2=$i=false;
   
$d=array(strlen($string), strlen($put));
    if(
$position > $d[0]) $position=$d[0];
    for(
$i=$d[0]; $i >= $position; $i--) $string[$i+$d[1]]=$string[$i];
    for(
$i=0; $i<$d[1]; $i++) $string[$position+$i]=$put[$i];
    return
$string;
}

// Explanation
$string='My dog dont love postman'; // string
$put="'"; // put ' on position
$position=10; // number of characters (position)
print_r( putinplace($string, $put, $position) );
?>

RESULT: My dog don't love postman

This is a small powerful function that performs its job flawlessly.
blessador at gmail dot com 18-Jun-2013 05:36
<?php
$price
= "12000";
$price = substr_replace ($price, ',', -3, 0)";
?>

ensure to remove the double quot  "
at the end of substr_replace ($price, ',', -3, 0)" in the above  code to avoid error.
elloromtz at gmail dot com 18-Apr-2010 08:23
It's worth noting that when start and length are both negative -and- the length is less than or equal to start, the length will have the effect of being set as 0.

<?php
substr_replace
('eggs','x',-1,-1); //eggxs
substr_replace('eggs','x',-1,-2); //eggxs
substr_replace('eggs','x',-1,-2); //eggxs
?>

Same as:
<?php
substr_replace
('eggs','x',-1,0); //eggxs
?>

<?php
substr_replace
('huevos','x',-2,-2); //huevxos
substr_replace('huevos','x',-2,-3); //huevxos
substr_replace('huevos','x',-2,-3); //huevxos
?>

Same as:
<?php
substr_replace
('huevos','x',-2,0); //huevxos
?>

Another note, if length is negative and start offsets the same position as length, length (yet again) will have the effect as being set as 0. (Of course, as mentioned in the manual, when length is negative it actually represents the position before it)

<?php
substr_replace
('abcd', 'x', 0, -4); //xabcd
?>

Same as:
<?php
substr_replace
('abcd','x',0,0); //xabcd
?>

<?php
substr_replace
('abcd', 'x', 1, -3); //axbcd
?>

Same as:
<?php
substr_replace
('abcd', 'x', 1, 0); //axbcd
?>
den dot gierling at web dot de 19-Feb-2010 07:32
My problem was that substr_replace() always added $replacement, so i wrote my own function.
This function only adds $replacement, if substr() took action.
The parameter $length is optional - like substr()'s.
Or I was too stupid using $start and $length...

<?php
function substr_replace_provided($string,$replacement,$start,$length=NULL)
{
   
$tmp=substr($string,$start,$length);
    if(
$string!==$tmp) {
       
$string = $tmp.$replacement;
    }
    return
$string;
}
?>
kalim dot fleet at gmail dot com 10-Oct-2009 06:49
This will truncate a longer string to a smaller string of specified length while replacing the middle portion with a separator exactly in the middle.

<?php

$longString
= 'abcdefghijklmnopqrstuvwxyz0123456789z.jpg';
$separator = '/.../';
$separatorlength = strlen($separator) ;
$maxlength = 25 - $separatorlength;
$start = $maxlength / 2 ;
$trunc strlen($longString) - $maxlength;

echo
substr_replace($longString, $separator, $start, $trunc);

//prints "abcdefghij/.../56789z.jpg"

?>
admiral at nuclearpixel dot com 06-Oct-2009 08:54
Hey everyone, I was noticing that there are a lot of ways below that people are using to write their own string truncation functions, but it kinda seemed like a lot of them went a bit too far out to make any sense to a n00b. Not that I am one anymore, but I though I'd add a note on this topic myself, in hopes that it might help others understand things a little better.

Here's a concept that some people don't know about, or remember to use often enough; You can actually pull individual characters out of a string by referencing that string as though it were an array. Example: If I have the string $s = 'cat', I can use $s[0] to actually get out only the first character of that string, 'c'. I use that same principle below, but I just use a loop to iterate through a string and add the characters to the output variable one by one until the $lenth param has been reached, or until the end of the string.

I hope this can help someone out!

-Admiral Potato

<?php

function admiralsTruncate($string, $length){
   
settype($string, 'string');
   
settype($length, 'integer');
    for(
$a = 0; $a < $length AND $a < strlen($string); $a++){
       
$output .= $string[$a];
    }
    return(
$output);
}

$my_string = 'cfcd208495d565ef66e7dff9f98764da';

echo
admiralsTruncate($my_string, 6);    // outputs: cfcd20

echo '<br>';

echo
admiralsTruncate($my_string, 9);    // outputs: cfcd20849

?>
billg AT microsoft.com 08-Apr-2009 04:31
Forget all of the mb_substr_replace() implementations mentioned in this page, they're all buggy.

Here is a version that mimics the behavior of substr_replace() exactly:

<?php

if (function_exists('mb_substr_replace') === false)
{
    function
mb_substr_replace($string, $replacement, $start, $length = null, $encoding = null)
    {
        if (
extension_loaded('mbstring') === true)
        {
           
$string_length = (is_null($encoding) === true) ? mb_strlen($string) : mb_strlen($string, $encoding);
           
            if (
$start < 0)
            {
               
$start = max(0, $string_length + $start);
            }
           
            else if (
$start > $string_length)
            {
               
$start = $string_length;
            }
           
            if (
$length < 0)
            {
               
$length = max(0, $string_length - $start + $length);
            }
           
            else if ((
is_null($length) === true) || ($length > $string_length))
            {
               
$length = $string_length;
            }
           
            if ((
$start + $length) > $string_length)
            {
               
$length = $string_length - $start;
            }
           
            if (
is_null($encoding) === true)
            {
                return
mb_substr($string, 0, $start) . $replacement . mb_substr($string, $start + $length, $string_length - $start - $length);
            }
           
            return
mb_substr($string, 0, $start, $encoding) . $replacement . mb_substr($string, $start + $length, $string_length - $start - $length, $encoding);
        }
       
        return (
is_null($length) === true) ? substr_replace($string, $replacement, $start) : substr_replace($string, $replacement, $start, $length);
    }
}

?>
juichenieder-phnet at yahoo dot co dot uk 25-Mar-2009 07:58
I've just taken a look at the post by ntoniazzi and I have a very small correction to make.

In the second if statement, it should be a triple equals, so:

<?php if ($length === null) ?>

It requires the triple equals, for the case of pure insertion, where $length = 0, the double equals, will catch this, causing the string to be cut short.  I hope this helps someone.
NiX0n at fragfest dot cx 09-Oct-2008 06:41
The preemptive test to see if $string is "too long" shouldn't add strlen($replacement) to $max.  $max should represent the absolute maximum length of string returned.  The size of the $replacement is irrelevant in that determination.

The rest of the function (unchanged below) operates as defined above.  Meaning, the size of the $replacement is subtracted from the $max, so that the returned string is exactly the length of $max.

<?php
function truncate($string, $max = 20, $replacement = '')
{
    if (
strlen($string) <= $max)
    {
        return
$string;
    }
   
$leave = $max - strlen ($replacement);
    return
substr_replace($string, $replacement, $leave);
}
?>
spcl dot delivery at gmail dot com 28-Jul-2008 01:14
the version of my predecessor will add $rep even if the string is shorter than max. fixed version:

<?php
function truncate($string, $max = 20, $rep = '')
{
    if (
strlen($string) <= ($max + strlen($rep)))
    {
        return
$string;
    }
   
$leave = $max - strlen ($rep);
    return
substr_replace($string, $rep, $leave);
}
?>

To preserve the filename extension you can call it like this:

truncate([filename], 30, '...' . end(explode('.', [filename])))
eblejr AT phrebh DOT com 04-Jun-2008 05:42
PHP version of Java's removeCharAt() function:

<?php
function removeCharAt($str, $int){
  return
substr_replace($str,"",$int,1);
}
?>
William Barry 23-Apr-2008 09:18
I recently ran across a situation where I need to strip a heavily nested html list such that only the top level was preserved.  I started with a regular expression solution, but found that I kept matching the wrong closing ul with an outer opening ul.

This was my alternative solution, and it seems to work well:

<?php

function stripNestedLists($str)
{
   
$str2 = $str;
   
$lastStr = $str2;
   
    do
    {
       
// Find the first closing ul
       
$cul = strpos($str2, '</ul>');
       
$ul = 0;
       
$lastUL = 0;
        do
        {
           
// Find the next opening ul
           
$lastUL = $ul;
           
$ul = strpos($str2, '<ul', $ul+1);
        }
        while (
$ul !== false && $ul < $cul);
   
       
$lastStr = $str2;
       
$str2 = substr_replace($str2, '', $lastUL, $cul-$lastUL+5);
       
$str2 = trim($str2);
    }
    while (
strlen($str2) > 0);
   
    return
$lastStr;
}

?>

Hope this helps someone.
jaimthorn at yahoo dot com 26-Mar-2008 07:53
I recently needed a routine that would remove the characters in one string from another, like the regex

<?php
   $result
= preg_replace("/[$chars]/", "", $string);
?>

and I needed it to be fast, and accept pretty much all input.  The regex above won't work when strlen($chars) == 0.  I came up with this, admittedly pretty horrible-looking code, that is quite fast:

<?php

function RemoveChars($string, $chars)
{
    return isset(
$chars{0}) ? str_replace($chars{0}, "", strtr($string, $chars, str_pad($chars{0}, strlen($chars), $chars{0}))) : $string;
}

?>

According to my own measurements, the regex in ONLY faster for when strlen($chars) == 1; for longer strings, my routine is faster.  What does it do?  Let's say you want to remove the period, the comma and the exclamation mark from a string, like so:
$result = RemoveChars("Isn't this, like, totally neat..!?", ".?!");
The str_pad function creates a string equal in length to the string that contains the character to be removed, but consisting only of the first character of that string:
The input is ".,!"
The output is "..."
The strtr function translates all characters in the string-to-be-processed ("Isn't this...") that also occur in the input (".,!") to the characters in the same position in the output ("...").  In other words:
Isn't this, like, totally neat..!?
becomes
Isn't this. like. totally neat....
Finally, the first character from the input (".,!") which happens to be, again, the period, is removed from that string by the str_replace call:
Isn't this like totally neat?
The function needs to check is $chars has at least one character, or else the str_pad function will fail.  If it's empty, then the unprocessed string is returned.
ntoniazzi at sqli dot com 14-Feb-2008 10:07
Almost... In the previous note, change this :
<?php
   
function mb_substr_replace($string, $replacement, $start, $length=null, $encoding=null) {
        if (
$encoding == null) $encoding = mb_internal_encoding();
        if(
$start < 0) $start = mb_strlen($string) + $start;
    [...]
?>
alishahnovin at hotmail dot com 07-Aug-2007 09:56
I like the truncate function below...however, I found a few issues. Particularly if you have content that may have any kind of punctuation in it (?, !, ?!?, --, ..., .., ;, etc.)

The older function would end up looking like "blah blah?..." or "blah blah,..." which doesn't look so nice to me...

Here's my fix. It removes all trailing punctuation (that you include in the $punctuation string below) and then adds an ellipse. So even if it has an ellipse with 3 dots, 2 dots, 4 dots, it'll be removed, then re-added.

<?php
function truncate($text,$numb,$etc = "...") {
$text = html_entity_decode($text, ENT_QUOTES);
if (
strlen($text) > $numb) {
$text = substr($text, 0, $numb);
$text = substr($text,0,strrpos($text," "));

$punctuation = ".!?:;,-"; //punctuation you want removed

$text = (strspn(strrev($text),  $punctuation)!=0)
        ?
       
substr($text, 0, -strspn(strrev($text),  $punctuation))
        :
$text;

$text = $text.$etc;
}
$text = htmlentities($text, ENT_QUOTES);
return
$text;
}
?>

I also needed a sort of "middle" truncate. The above function truncates around the end, but if you want to truncate around the middle (ie "Hello this is a long string." --> "Hello this ... long string.") you can use this (requires the truncate function):

<?php
function mtruncate($text, $numb, $etc = " ... ") {
   
$first_part = truncate(truncate($text, strlen($text)/2, ""), $numb/2, "");
   
$second_part = truncate(strrev(truncate(strrev($text), strlen($text)/2, "")), $numb/2, "");
    return
$first_part.$etc.$second_part;
}
?>
chuayw2000 at hotmail dot com 09-Dec-2005 12:33
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);
            }
        }
    }
}
?>
hermes at andycostell dot com 27-Aug-2005 08:48
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 09:44
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)
danieldoorduin at hotmail dot com 10-Dec-2004 11:48
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
dmron 18-Jun-2004 01:34
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;
}
tony at outshine dot com 10-May-2004 11:25
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 04:33
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) 20-Jan-2004 08:05
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;
}
?>
david at ethinkn dot com 06-Jul-2003 02:36
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 12:01
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 13-Feb-2002 07:38
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 05:30
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 16-Apr-2001 09:16
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);

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