substr_replace

(PHP 4, PHP 5)

substr_replace文字列の一部を置換する

説明

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

substr_replace()は、文字列 stringstart および (オプションの) length パラメータで区切られた部分を replacement で指定した文字列に置換します。

パラメータ

string

入力文字列。

文字列の配列を指定することもでき、各文字列について順に置換を行います。 この場合、他のパラメータ replacementstart および length がスカラ値なら それを各入力文字列に順次適用し、配列なら各入力文字列に対応する要素の値を適用します。

replacement

置換する文字列。

start

start が正の場合、置換は stringstart 番目の文字から始まります。

start が負の場合、置換は string の終端から start 番目の文字から始まります。

length

正の値を指定した場合、 string の置換される部分の長さを表します。 負の場合、置換を停止する位置が string の終端から何文字目であるかを表します。このパラメータが省略された場合、 デフォルト値は strlen(string)、すなわち、 string の終端まで置換することになります。 当然、もし length がゼロだったら、 この関数は string の最初から start の位置に replacement を挿入するということになります。

返り値

結果の文字列を返します。もし、string が配列の場合、配列が返されます。

例1 シンプルな substr_replace() の例

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

/* 以下の2つの例は、全ての $var で 'bob' で置換します。 */
echo substr_replace($var'bob'0) . "<br />\n";
echo 
substr_replace($var'bob'0strlen($var)) . "<br />\n";

/* $var の先頭に 'bob' を挿入します */
echo substr_replace($var'bob'00) . "<br />\n";

/* 次の2つの例は、$var の 'MNRPQR' を 'bob'で置換します */
echo substr_replace($var'bob'10, -1) . "<br />\n";
echo 
substr_replace($var'bob', -7, -1) . "<br />\n";

/* $var から 'MNRPQR' を削除します */
echo substr_replace($var''10, -1) . "<br />\n";
?>

例2 substr_replace() で複数の文字列を一度に置換する例

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

// シンプルなケース: 各文字列の XXX を YYY で置換します
echo implode('; 'substr_replace($input'YYY'33))."\n";

// より複雑で、各文字列で置換する値が異なるケース
$replace = array('AAA''BBB''CCC');
echo 
implode('; 'substr_replace($input$replace33))."\n";

// 置換する文字数が異なるケース
$length = array(123);
echo 
implode('; 'substr_replace($input$replace3$length))."\n";
?>

上の例の出力は以下となります。

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

注意

注意: この関数はバイナリデータに対応しています。

参考

add a note add a note

User Contributed Notes 28 notes

up
5
ivijan dot stefan at gmail dot com
8 months ago
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.
up
7
juichenieder-phnet at yahoo dot co dot uk
5 years ago
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.
up
4
elloromtz at gmail dot com
4 years ago
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
?>
up
2
chuayw2000 at hotmail dot com
8 years ago
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);
            }
        }
    }
}
?>
up
1
billg AT microsoft.com
5 years ago
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);
    }
}

?>
up
2
klaas at group94 dot com
12 years ago
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...
up
1
den dot gierling at web dot de
4 years ago
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;
}
?>
up
1
kalim dot fleet at gmail dot com
5 years ago
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"

?>
up
1
William Barry
6 years ago
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.
up
1
ntoniazzi at sqli dot com
6 years ago
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;
    [...]
?>
up
1
hermes at andycostell dot com
9 years ago
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);
up
0
blessador at gmail dot com
1 year ago
<?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.
up
0
NiX0n at fragfest dot cx
6 years ago
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);
}
?>
up
0
spcl dot delivery at gmail dot com
6 years ago
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])))
up
0
eblejr AT phrebh DOT com
6 years ago
PHP version of Java's removeCharAt() function:

<?php
function removeCharAt($str, $int){
  return
substr_replace($str,"",$int,1);
}
?>
up
0
Guru Evi
9 years ago
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)
up
0
danieldoorduin at hotmail dot com
9 years ago
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
up
0
dmron
10 years ago
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;
}
up
0
tony at outshine dot com
10 years ago
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;
}
?>
up
0
geniusdex ( at ) brz ( dot ) nu
10 years ago
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);
    }
}
?>
up
0
Thijs Wijnmaalen (thijs[at]nllinux.nl)
10 years ago
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;
}
?>
up
0
david at ethinkn dot com
11 years ago
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)

?>
up
0
thomasNOSPAM at sportentranceNOSPAM dot com
12 years ago
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...
up
0
Anonymous
13 years ago
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);
up
0
mrbrown8 at juno dot com
13 years ago
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);
up
-1
admiral at nuclearpixel dot com
5 years ago
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

?>
up
-1
alishahnovin at hotmail dot com
7 years ago
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;
}
?>
up
-1
jaimthorn at yahoo dot com
6 years ago
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.
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