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substr

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

substr — 文字列の一部分を返す

説明

substr(string $string, int $offset, ?int $length = null): string

文字列 string の、offset で指定された位置から length バイト分の文字列を返します。

パラメータ

string

入力文字列。

offset

offset が正の場合、返される文字列は、 string の 0 から数えて offset番目から始まる文字列となります。例えば、文字列'abcdef'において位置 0にある文字は、'a'であり、位置2には'c'があります。

offset が負の場合、返される文字列は、 stringの後ろから数えて offset番目から始まる文字列となります。

string の長さが offset 文字より短い場合は、空の文字列が返されます。

例1 負の offset の使用

<?php
$rest = substr("abcdef", -1);    // "f" を返す
$rest = substr("abcdef", -2);    // "ef" を返す
$rest = substr("abcdef", -3, 1); // "d" を返す
?>

length

length が指定され、かつ正である場合、返される文字列は offset (string の長さに依存します) から数えてlength文字数分となります。

length が指定され、かつ負である場合、 string の終端からその文字数分の文字が省略されます (offset が負の場合は、開始位置を算出したあとで)。もし offset が切り出し位置を超える場合、空の文字列が返されます。

length が指定され、かつ 0 であれば、空の文字が返されます。

length を省略した場合、または null の場合は、 offset の位置から文字列の最後までの部分文字列を返します。

例2 負の length の使用

<?php
$rest = substr("abcdef", 0, -1);  // "abcde" を返す
$rest = substr("abcdef", 2, -1);  // "cde" を返す
$rest = substr("abcdef", 4, -4);  // "" を返す。PHP 8.0.0 より前のバージョンでは、false を返していました。
$rest = substr("abcdef", -3, -1); // "de" を返す
?>

戻り値

string の一部を返すか、空文字列を返します。

変更履歴

バージョン	説明
8.0.0	`length` は、nullable になりました。 `length` に明示的に `null` を設定すると、文字列の最後までを含む部分文字列を返すようになっています。これより前のバージョンでは、空文字列を返していました。
8.0.0	この関数は、前のバージョンで `false` を返す場合に、空文字列を返すようになりました。

例

例3 基本的な substr() の使用法

<?php
echo substr('abcdef', 1);     // bcdef
echo substr("abcdef", 1, null); // bcdef, PHP 8.0.0 より前のバージョンでは、空の文字列を返していました。
echo substr('abcdef', 1, 3);  // bcd
echo substr('abcdef', 0, 4);  // abcd
echo substr('abcdef', 0, 8);  // abcdef
echo substr('abcdef', -1, 1); // f

// 文字列中の 1 文字にアクセスすることも
// "角括弧" を使用することで可能
$string = 'abcdef';
echo $string[0];                 // a
echo $string[3];                 // d
echo $string[strlen($string)-1]; // f

?>

例4 substr() でのキャストの挙動

<?php
class apple {
    public function __toString() {
        return "green";
    }
}

echo "1) ".var_export(substr("pear", 0, 2), true).PHP_EOL;
echo "2) ".var_export(substr(54321, 0, 2), true).PHP_EOL;
echo "3) ".var_export(substr(new apple(), 0, 2), true).PHP_EOL;
echo "4) ".var_export(substr(true, 0, 1), true).PHP_EOL;
echo "5) ".var_export(substr(false, 0, 1), true).PHP_EOL;
echo "6) ".var_export(substr("", 0, 1), true).PHP_EOL;
echo "7) ".var_export(substr(1.2e3, 0, 4), true).PHP_EOL;
?>

上の例の出力は以下となります。

1) 'pe'
2) '54'
3) 'gr'
4) '1'
5) ''
6) ''
7) '1200'

例5 文字列の範囲が不正な場合

指定された文字列の範囲が正しくない場合、 substr() は PHP 8.0.0 以降では空文字列を返します。それより前のバージョンでは、false を返していました。

<?php
var_dump(substr('a', 2));
?>

上の例の PHP 8 での出力は、このようになります。:

string(0) ""

上の例の PHP 7 での出力は、このようになります。

bool(false)

参考

strrchr() - 文字列中に文字が最後に現れる場所を取得する
substr_replace() - 文字列の一部を置換する
preg_match() - 正規表現によるマッチングを行う
trim() - 文字列の先頭および末尾にあるホワイトスペースを取り除く
mb_substr() - 文字列の一部を得る
wordwrap() - 指定した文字数で文字列を分割する
文字列への文字単位のアクセスと修正

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User Contributed Notes 34 notes

down

180

Andreas Bur (andreas dot buro at gmail dot com) ¶

15 years ago

For getting a substring of UTF-8 characters, I highly recommend mb_substr

<?php
        $utf8string = "cakeæøå";

        echo substr($utf8string,0,5);
        // output cake#
        echo mb_substr($utf8string,0,5,'UTF-8');
        //output cakeæ
?>

down

116

biohazard dot ge at gmail dot com ¶

11 years ago

may be by following functions will be easier to extract the needed sub parts from a string:

<?php
after ('@', 'biohazard@online.ge');
//returns 'online.ge'
//from the first occurrence of '@'

before ('@', 'biohazard@online.ge');
//returns 'biohazard'
//from the first occurrence of '@'

between ('@', '.', 'biohazard@online.ge');
//returns 'online'
//from the first occurrence of '@'

after_last ('[', 'sin[90]*cos[180]');
//returns '180]'
//from the last occurrence of '['

before_last ('[', 'sin[90]*cos[180]');
//returns 'sin[90]*cos['
//from the last occurrence of '['

between_last ('[', ']', 'sin[90]*cos[180]');
//returns '180'
//from the last occurrence of '['
?>

here comes the source:

<?php

    function after ($this, $inthat)
    {
        if (!is_bool(strpos($inthat, $this)))
        return substr($inthat, strpos($inthat,$this)+strlen($this));
    };

    function after_last ($this, $inthat)
    {
        if (!is_bool(strrevpos($inthat, $this)))
        return substr($inthat, strrevpos($inthat, $this)+strlen($this));
    };

    function before ($this, $inthat)
    {
        return substr($inthat, 0, strpos($inthat, $this));
    };

    function before_last ($this, $inthat)
    {
        return substr($inthat, 0, strrevpos($inthat, $this));
    };

    function between ($this, $that, $inthat)
    {
        return before ($that, after($this, $inthat));
    };

    function between_last ($this, $that, $inthat)
    {
     return after_last($this, before_last($that, $inthat));
    };

// use strrevpos function in case your php version does not include it
function strrevpos($instr, $needle)
{
    $rev_pos = strpos (strrev($instr), strrev($needle));
    if ($rev_pos===false) return false;
    else return strlen($instr) - $rev_pos - strlen($needle);
};
?>

down

greg at apparel dot com ¶

11 years ago

Coming to PHP from classic ASP I am used to the Left() and Right() functions built into ASP so I did a quick PHPversion. hope these help someone else making the switch

function left($str, $length) {
    return substr($str, 0, $length);
}

function right($str, $length) {
    return substr($str, -$length);
}

down

pugazhenthi k ¶

11 years ago

<?Php 

### SUB STRING  BY WORD USING substr() and strpos()  #####

### THIS SCRIPT WILL RETURN PART OF STRING  WITHOUT WORD BREAK ###

$description = ‘your description here your description here your description here your description here your description here your description here your description hereyour description here your description here’  // your description here .

$no_letter = 30 ;

if(strlen($desctiption) > 30 )
{
     echo substr($description,0,strpos($description,’ ‘,30));             //strpos to find ‘ ‘ after 30 characters.
}
else {
     echo $description;
}

?>

down

fatihmertdogancan at hotmail dot com ¶

10 years ago

[English]
I created python similar accesing list or string with php substr & strrev functions.

Use: str($string,$pattern)

About the python pattern,
http://docs.python.org/release/1.5.1p1/tut/strings.html
http://effbot.org/zone/python-list.htm

About of pattern structures
[start:stop:step]

Example,
<?php
$s = "fatihmertdogancan";
echo str($s,"1:9:-2");
echo "<br/>";
echo str($s,"1:-3:-2");
echo "<br/>";
echo str($s,"1:-11:-5");
echo "<br/>";
echo str($s,"1:9:4");
?>

Output,
thetoacn
eht
aom
htan

This is function phpfiddle link: http://phpfiddle.org/main/code/e82-y5d

or source;

<?php
    function str($str,$pattern){
        //[start:stop:step]
        //pattern ->            ([-]?[0-9]*|\s):([-]?[0-9]*|\s):([-]?[0-9]*|\s)
        preg_match("/([-]?[0-9]*|\s?):([-]?[0-9]*|\s?):?([-]?[0-9]*|\s?)/", $pattern, $yakala);
        $start = $yakala[1];
        $stop = $yakala[2];
        $step = $yakala[3];
        
        if(empty($start) && empty($stop) && $step == "-1"){//istisna durum
            return strrev($str);
        }else if(empty($start) && empty($stop) && isset($step)){//istisna durum
            $rev = "";
            $yeni = "";
            if($step[0] == "-" && $stop != "-1"){$rev = "VAR";}
            $atla = abs($step);
            for($i = 0; $i <= strlen($str); $i++){
                $offset = $i*$atla;
                if(isset($str[$offset])){
                    $yeni = $yeni.$str[$offset];
                }
            }
            if($rev != "VAR"){
                return substr($yeni,0,strlen($str)-1);
                //"hepsi boş, step dolu o da +";
            }else{
                return strrev(substr($yeni,0,strlen($str)-1));
                //"hepsi boş, step dolu o da -";
            }
        }
        
        if(empty($start) && empty($stop) && empty($step)){
            return $str;
            //"hepsi boş";
        }else if(empty($start)){
            if(isset($stop) && empty($step)){
                $rev = "";
                if($stop[0] == "-"){$rev = "VAR";}
                if($rev != "VAR"){
                    return substr($str,0,$stop);
                    //"start ve step boş, stop dolu"
                }else{
                    return strrev(substr($str,0,$stop));
                    //"start ve step boş, stop -1";
                }
            }else if(isset($stop) && isset($step)){
                $rev = "";
                if($stop[0] == "-"){$rev = "VAR";}
                $yeni = "";
                if($step == 1){
                    if($rev != "VAR"){
                        return $str;
                        //"start boş, stop ve step dolu, step 1";
                    }else{
                        return strrev(substr($str,0,abs($stop))); //abs -> mutlak değer (-5 = 5)
                        //"start boş, stop -, step dolu, step 1";
                    }
                }else{
                    $atla = abs($step);
                    for($i = 0; $i <= strlen($str); $i++){
                        $offset = $i*$atla;
                        if(isset($str[$offset])){
                            $yeni = $yeni.$str[$offset];
                        }
                    }
                    if($rev != "VAR"){
                        return substr($yeni,0,$stop);
                        //"start boş, step ve stop dolu";
                    }else{
                        return strrev(substr($yeni,0,abs($stop)));
                        //"start boş, step ve stop -";
                    }
                }
            }
        //start boş değilse
        }else if(!empty($start)){
            if(isset($stop) && empty($step)){
                $rev = "";
                if($stop[0] == "-"){$rev = "VAR";}
                if($rev != "VAR"){
                    return substr($str,$start,$stop);
                    //return "step boş, start ve stop dolu";
                }else{
                    return strrev(substr($str,0,abs($stop)));
                    //"step boş, start ve stop dolu, stop -";
                }
            }else if(isset($stop) && isset($step)){
                
                //hepsi dolu
                $rev = "";
                if($stop[0] == "-"){$rev = "VAR";}
                $yeni = "";
                if($step == 1){
                    if($rev != "VAR"){
                        return substr($str,$start,$stop);
                        //"hepsi dolu, step 1";
                    }else{
                        return substr($str,$start,abs($stop));
                        //"hepsi dolu, step 1, stop -";
                    }
                }else{
                    if($stop[0] == "-"){$rev = "VAR";}
                    $atla = abs($step);
                    for($i = 0; $i <= strlen($str); $i++){
                        $offset = $i*$atla;
                        if(isset($str[$offset])){
                            $yeni = $yeni.$str[$offset];
                        }
                    }
                    if($rev != "VAR"){
                        return substr($yeni,$start,$stop);
                        //"hepsi dolu";
                    }else{
                        return strrev(substr($yeni,$start,abs($stop)));
                        //"hepsi dolu, stop -";
                    }
                }
            }
        }
    }
?>

Good works..

down

bleakwind at msn dot com ¶

19 years ago

This returns the portion of str specified by the start and length parameters..
It can performs multi-byte safe on number of characters. like mb_strcut() ...

Note:
1.Use it like this bite_str(string str, int start, int length [,byte of on string]);
2.First character's position is 0. Second character position is 1, and so on...
3.$byte is one character length of your encoding, For example: utf-8 is "3", gb2312 and big5 is "2"...you can use the function strlen() get it... 
Enjoy it :) ...

--- Bleakwind
QQ:940641
http://www.weaverdream.com

PS:I'm sorry my english is too poor... :( 

<?php
// String intercept By Bleakwind
// utf-8:$byte=3 | gb2312:$byte=2 | big5:$byte=2
function bite_str($string, $start, $len, $byte=3)
{
    $str     = "";
    $count   = 0;
    $str_len = strlen($string);
    for ($i=0; $i<$str_len; $i++) {
        if (($count+1-$start)>$len) {
            $str  .= "...";
            break;
        } elseif ((ord(substr($string,$i,1)) <= 128) && ($count < $start)) {
            $count++;
        } elseif ((ord(substr($string,$i,1)) > 128) && ($count < $start)) {
            $count = $count+2;
            $i     = $i+$byte-1;
        } elseif ((ord(substr($string,$i,1)) <= 128) && ($count >= $start)) {
            $str  .= substr($string,$i,1);
            $count++;
        } elseif ((ord(substr($string,$i,1)) > 128) && ($count >= $start)) {
            $str  .= substr($string,$i,$byte);
            $count = $count+2;
            $i     = $i+$byte-1;
        }
    }
    return $str;
}

// Test
$str = "123456???ֽ?123456?ַ???123456??ȡ????";
for($i=0;$i<30;$i++){
    echo "<br>".bite_str($str,$i,20);    
}
?>

down

Petez ¶

17 years ago

I wanted to work out the fastest way to get the first few characters from a string, so I ran the following experiment to compare substr, direct string access and strstr:

<?php
/* substr access */
beginTimer();
for ($i = 0; $i < 1500000; $i++){
    $opening = substr($string,0,11);
    if ($opening == 'Lorem ipsum'){
        true;
    }else{
        false;
    }
}
$endtime1 = endTimer();

/* direct access */
beginTimer();
for ($i = 0; $i < 1500000; $i++){
    if ($string[0] == 'L' && $string[1] == 'o' && $string[2] == 'r' && $string[3] == 'e' && $string[4] == 'm' && $string[5] == ' ' && $string[6] == 'i' && $string[7] == 'p' && $string[8] == 's' && $string[9] == 'u' && $string[10] == 'm'){
        true;
    }else{
        false;
    }
}
$endtime2 = endTimer();

/* strstr access */
beginTimer();
for ($i = 0; $i < 1500000; $i++){
    $opening = strstr($string,'Lorem ipsum');
    if ($opening == true){
        true;
    }else{
        false;
    }
}
$endtime3 = endTimer();

echo $endtime1."\r\n".$endtime2."\r\n".$endtime3;
?>

The string was 6 paragraphs of Lorem Ipsum, and I was trying match the first two words. The experiment was run 3 times and averaged. The results were:

(substr) 3.24
(direct access) 11.49
(strstr) 4.96

(With standard deviations 0.01, 0.02 and 0.04)

THEREFORE substr is the fastest of the three methods for getting the first few letters of a string.

down

nikolai dot wuestemann at t-online dot de ¶

13 years ago

If you want to have a string BETWEEN two strings, just use this function:



<?php

function get_between($input, $start, $end)

{

  $substr = substr($input, strlen($start)+strpos($input, $start), (strlen($input) - strpos($input, $end))*(-1));

  return $substr;

}



//Example:



$string = "123456789";

$a = "12";

$b = "9";



echo get_between($string, $a, $b);



//Output:

//345678

?>

down

Anonymous ¶

7 years ago

Be aware of a slight inconsistency between substr and mb_substr

mb_substr("", 4);      returns empty string

substr("", 4);              returns boolean false

tested in PHP 7.1.11 (Fedora 26) and PHP 5.4.16 (CentOS 7.4)

down

egingell at sisna dot com ¶

18 years ago

<?php

/**
 * string substrpos(string $str, mixed $start [[, mixed $end], boolean $ignore_case])
 *
 * If $start is a string, substrpos will return the string from the position of the first occuring $start to $end
 *
 * If $end is a string, substrpos will return the string from $start to the position of the first occuring $end
 *
 * If the first character in (string) $start or (string) $end is '-', the last occuring string will be used.
 *
 * If $ignore_case is true, substrpos will not care about the case.
 * If $ignore_case is false (or anything that is not (boolean) true, the function will be case sensitive.
 *        Both of the above: only applies if either $start or $end are strings.
 *
 * echo substrpos('This is a string with 0123456789 numbers in it.', 5, '5');
 *        // Prints 'is a string with 01234';
 *
 * echo substrpos('This is a string with 0123456789 numbers in it.', '5', 5);
 *        // Prints '56789'
 *
 * echo substrpos('This is a string with 0123456789 numbers in it and two strings.', -60, '-string')
 *        // Prints 's is a string with 0123456789 numbers in it and two '
 *
 * echo substrpos('This is a string with 0123456789 numbers in it and two strings.', -60, '-STRING', true)
 *        // Prints 's is a string with 0123456789 numbers in it and two '
 *
 * echo substrpos('This is a string with 0123456789 numbers in it and two strings.', -60, '-STRING', false)
 *        // Prints 's is a string with 0123456789 numbers in it and two strings.'
 *
 * Warnings:
 *        Since $start and $end both take either a string or an integer:
 *            If the character or string you are searching $str for is a number, pass it as a quoted string.
 *        If $end is (integer) 0, an empty string will be returned.
 *        Since this function takes negative strings ('-search_string'):
 *            If the string your using in $start or $end is a '-' or begins with a '-' escape it with a '\'.
 *            This only applies to the *first* character of $start or $end.
 */

// Define stripos() if not defined (PHP < 5).
if (!is_callable("stripos")) {
    function stripos($str, $needle, $offset = 0) {
        return strpos(strtolower($str), strtolower($needle), $offset);
    }
}

function substrpos($str, $start, $end = false, $ignore_case = false) {
    // Use variable functions
    if ($ignore_case === true) {
        $strpos = 'stripos'; // stripos() is included above in case it's not defined (PHP < 5).
    } else {
        $strpos = 'strpos';
    }

    // If end is false, set it to the length of $str
    if ($end === false) {
        $end = strlen($str);
    }

    // If $start is a string do what's needed to make it an integer position for substr().
    if (is_string($start)) {
        // If $start begins with '-' start processing until there's no more matches and use the last one found.
        if ($start{0} == '-') {
            // Strip off the '-'
            $start = substr($start, 1);
            $found = false;
            $pos = 0;
            while(($curr_pos = $strpos($str, $start, $pos)) !== false) {
                $found = true;
                $pos = $curr_pos + 1;
            }
            if ($found === false) {
                $pos = false;
            } else {
                $pos -= 1;
            }
        } else {
            // If $start begins with '\-', strip off the '\'.
            if ($start{0} . $start{1} == '\-') {
                $start = substr($start, 1);
            }
            $pos = $strpos($str, $start);
        }
        $start = $pos !== false ? $pos : 0;
    }

    // Chop the string from $start to strlen($str).
    $str = substr($str, $start);

    // If $end is a string, do exactly what was done to $start, above.
    if (is_string($end)) {
        if ($end{0} == '-') {
            $end = substr($end, 1);
            $found = false;
            $pos = 0;
            while(($curr_pos = strpos($str, $end, $pos)) !== false) {
                $found = true;
                $pos = $curr_pos + 1;
            }
            if ($found === false) {
                $pos = false;
            } else {
                $pos -= 1;
            }
        } else {
            if ($end{0} . $end{1} == '\-') {
                $end = substr($end, 1);
            }
            $pos = $strpos($str, $end);
        }
        $end = $pos !== false ? $pos : strlen($str);
    }

    // Since $str has already been chopped at $start, we can pass 0 as the new $start for substr()
    return substr($str, 0, $end);
}

?>

down

fanfatal at fanfatal dot pl ¶

19 years ago

Hmm ... this is a script I wrote, whitch is very similar to substr, but it isn't takes html and bbcode for counting and it takes portion of string and show avoided (html & bbcode) tags too ;] 

Specially usefull for show part of serach result included html and bbcode tags



<?php



/**

 * string csubstr ( string string, int start [, int length] )

 *

 * @author FanFataL

 * @param string string

 * @param int start

 * @param [int length]

 * @return string

 */

function csubstr($string, $start, $length=false) {

    $pattern = '/(\[\w+[^\]]*?\]|\[\/\w+\]|<\w+[^>]*?>|<\/\w+>)/i';

    $clean = preg_replace($pattern, chr(1), $string);

    if(!$length)

        $str = substr($clean, $start);

    else {

        $str = substr($clean, $start, $length);

        $str = substr($clean, $start, $length + substr_count($str, chr(1)));

    }

    $pattern = str_replace(chr(1),'(.*?)',preg_quote($str));

    if(preg_match('/'.$pattern.'/is', $string, $matched))

        return $matched[0];

    return $string;

}



?>



Using this is similar to simple substr.



Greatings ;]

...

down

kaysar in ymail in com ¶

15 years ago

Drop extensions of a file (even from a file location string)

<?php

$filename = "c:/some dir/abc defg. hi.jklmn";

echo substr($filename, 0, (strlen ($filename)) - (strlen (strrchr($filename,'.'))));

?>

output: c:/some dir/abc defg. hi

Hope it may help somebody like me.. (^_^)

Atelier ”慶”

WEBクリエイター歴２０年、最先端技術と安心をお届けします。

PHPのお勉強！

substr

説明

パラメータ

戻り値

変更履歴

例

参考

Found A Problem?

User Contributed Notes 34 notes