strpos

(PHP 4, PHP 5)

strposFind the position of the first occurrence of a substring in a string

Description

mixed strpos ( string $haystack , mixed $needle [, int $offset = 0 ] )

Find the numeric position of the first occurrence of needle in the haystack string.

Parameters

haystack

The string to search in.

needle

If needle is not a string, it is converted to an integer and applied as the ordinal value of a character.

offset

If specified, search will start this number of characters counted from the beginning of the string. Unlike strrpos() and strripos(), the offset cannot be negative.

Return Values

Returns the position of where the needle exists relative to the beginning of the haystack string (independent of offset). Also note that string positions start at 0, and not 1.

Returns FALSE if the needle was not found.

Warning

This function may return Boolean FALSE, but may also return a non-Boolean value which evaluates to FALSE. Please read the section on Booleans for more information. Use the === operator for testing the return value of this function.

Examples

Example #1 Using ===

<?php
$mystring 
'abc';
$findme   'a';
$pos strpos($mystring$findme);

// Note our use of ===.  Simply == would not work as expected
// because the position of 'a' was the 0th (first) character.
if ($pos === false) {
    echo 
"The string '$findme' was not found in the string '$mystring'";
} else {
    echo 
"The string '$findme' was found in the string '$mystring'";
    echo 
" and exists at position $pos";
}
?>

Example #2 Using !==

<?php
$mystring 
'abc';
$findme   'a';
$pos strpos($mystring$findme);

// The !== operator can also be used.  Using != would not work as expected
// because the position of 'a' is 0. The statement (0 != false) evaluates 
// to false.
if ($pos !== false) {
     echo 
"The string '$findme' was found in the string '$mystring'";
         echo 
" and exists at position $pos";
} else {
     echo 
"The string '$findme' was not found in the string '$mystring'";
}
?>

Example #3 Using an offset

<?php
// We can search for the character, ignoring anything before the offset
$newstring 'abcdef abcdef';
$pos strpos($newstring'a'1); // $pos = 7, not 0
?>

Notes

Note: This function is binary-safe.

See Also

  • stripos() - Find the position of the first occurrence of a case-insensitive substring in a string
  • strrpos() - Find the position of the last occurrence of a substring in a string
  • strripos() - Find the position of the last occurrence of a case-insensitive substring in a string
  • strstr() - Find the first occurrence of a string
  • strpbrk() - Search a string for any of a set of characters
  • substr() - Return part of a string
  • preg_match() - Perform a regular expression match

Коментарии

Автор:
Code like this:
<?php
if (strpos('this is a test''is') !== false) {
    echo 
"found it";
}
?>

gets repetitive, is not very self-explanatory, and most people handle it incorrectly anyway. Make your life easier:

<?php
function str_contains($haystack$needle$ignoreCase false) {
    if (
$ignoreCase) {
       
$haystack strtolower($haystack);
       
$needle   strtolower($needle);
    }
   
$needlePos strpos($haystack$needle);
    return (
$needlePos === false false : ($needlePos+1));
}
?>

Then, you may do:
<?php
// simplest use
if (str_contains('this is a test''is')) {
    echo 
"Found it";
}

// when you need the position, as well whether it's present
$needlePos str_contains('this is a test''is');
if (
$needlePos) {
    echo 
'Found it at position ' . ($needlePos-1);
}

// you may also ignore case
$needlePos str_contains('this is a test''IS'true);
if (
$needlePos) {
    echo 
'Found it at position ' . ($needlePos-1);
}
?>
2004-04-21 18:38:36
http://php5.kiev.ua/manual/ru/function.strpos.html
Автор:
Many people look for in_string which does not exist in PHP, so, here's the most efficient form of in_string() (that works in both PHP 4/5) that I can think of:
<?php
function in_string($needle$haystack$insensitive false) {
    if (
$insensitive) {
        return 
false !== stristr($haystack$needle);
    } else {
        return 
false !== strpos($haystack$needle);
    }
}
?>
2004-08-25 18:52:25
http://php5.kiev.ua/manual/ru/function.strpos.html
if you want to get the position of a substring relative to a substring of your string, BUT in REVERSE way:

<?php

function strpos_reverse_way($string,$charToFind,$relativeChar) {
   
//
   
$relativePos strpos($string,$relativeChar);
   
$searchPos $relativePos;
   
$searchChar '';
   
//
   
while ($searchChar != $charToFind) {
       
$newPos $searchPos-1;
       
$searchChar substr($string,$newPos,strlen($charToFind));
       
$searchPos $newPos;
    }
   
//
   
if (!empty($searchChar)) {
       
//
       
return $searchPos;
        return 
TRUE;
    }
    else {
        return 
FALSE;
    }
   
//
}

?>
2006-10-14 13:58:24
http://php5.kiev.ua/manual/ru/function.strpos.html
This is a bit more useful when scanning a large string for all occurances between 'tags'.

<?php
function getStrsBetween($s,$s1,$s2=false,$offset=0) {
   
/*====================================================================
    Function to scan a string for items encapsulated within a pair of tags

    getStrsBetween(string, tag1, <tag2>, <offset>

    If no second tag is specified, then match between identical tags

    Returns an array indexed with the encapsulated text, which is in turn
    a sub-array, containing the position of each item.

    Notes:
    strpos($needle,$haystack,$offset)
    substr($string,$start,$length)

    ====================================================================*/

   
if( $s2 === false ) { $s2 $s1; }
   
$result = array();
   
$L1 strlen($s1);
   
$L2 strlen($s2);

    if( 
$L1==|| $L2==) {
        return 
false;
    }

    do {
       
$pos1 strpos($s,$s1,$offset);

        if( 
$pos1 !== false ) {
           
$pos1 += $L1;

           
$pos2 strpos($s,$s2,$pos1);

            if( 
$pos2 !== false ) {
               
$key_len $pos2 $pos1;

               
$this_key substr($s,$pos1,$key_len);

                if( !
array_key_exists($this_key,$result) ) {
                   
$result[$this_key] = array();
                }

               
$result[$this_key][] = $pos1;

               
$offset $pos2 $L2;
            } else {
               
$pos1 false;
            }
        }
    } while(
$pos1 !== false );

    return 
$result;
}
?>
2007-05-15 05:21:48
http://php5.kiev.ua/manual/ru/function.strpos.html
WARNING

As strpos may return either FALSE (substring absent) or 0 (substring at start of string), strict versus loose equivalency operators must be used very carefully.

To know that a substring is absent, you must use: 

=== FALSE

To know that a substring is present (in any position including 0), you can use either of:

!== FALSE  (recommended)
 > -1  (note: or greater than any negative number)

To know that a substring is at the start of the string, you must use: 

=== 0

To know that a substring is in any position other than the start, you can use any of: 

 > 0  (recommended)
!= 0  (note: but not !== 0 which also equates to FALSE)
!= FALSE  (disrecommended as highly confusing)

Also note that you cannot compare a value of "" to the returned value of strpos. With a loose equivalence operator (== or !=) it will return results which don't distinguish between the substring's presence versus position. With a strict equivalence operator (=== or !==) it will always return false.
2008-01-11 17:45:32
http://php5.kiev.ua/manual/ru/function.strpos.html
This might be useful.

<?php
class String{
   
   
//Look for a $needle in $haystack in any position
   
public static function contains(&$haystack, &$needle, &$offset)
    {
       
$result strpos($haystack$needle$offset);
        return 
$result !== FALSE;
    }
   
   
//intuitive implementation .. if not found returns -1.
   
public static function strpos(&$haystack, &$needle, &$offset)
    {
       
$result strpos($haystack$needle$offset);
        if (
$result === FALSE )
        {
            return -
1;
        }
        return 
$result;
    }
   
}
//String
?>
2008-04-01 19:17:34
http://php5.kiev.ua/manual/ru/function.strpos.html
Автор:
If you would like to find all occurences of a needle inside a haystack you could use this function strposall($haystack,$needle);. It will return an array with all the strpos's.

<?php
/**
 * strposall
 * 
 * Find all occurrences of a needle in a haystack
 *
 * @param string $haystack
 * @param string $needle
 * @return array or false
 */
function strposall($haystack,$needle){
   
   
$s=0;
   
$i=0;
   
    while (
is_integer($i)){
       
       
$i strpos($haystack,$needle,$s);
       
        if (
is_integer($i)) { 
           
$aStrPos[] = $i
           
$s $i+strlen($needle); 
        }
    }
    if (isset(
$aStrPos)) { 
        return 
$aStrPos
    } 
    else { 
        return 
false
    }
}
?>
2008-11-17 19:52:32
http://php5.kiev.ua/manual/ru/function.strpos.html
routine to return -1 if there is no match for strpos

<?php
//instr function to mimic vb instr fucntion
function InStr($haystack$needle)
{
   
$pos=strpos($haystack$needle);
    if (
$pos !== false)
    {
        return 
$pos;
    }
    else
    {
        return -
1;
    }
}
?>
2009-03-23 11:48:06
http://php5.kiev.ua/manual/ru/function.strpos.html
A strpos modification to return an array of all the positions of a needle in the haystack 

<?php
function strallpos($haystack,$needle,$offset 0){
   
$result = array();
    for(
$i $offset$i<strlen($haystack); $i++){
       
$pos strpos($haystack,$needle,$i);
        if(
$pos !== FALSE){
           
$offset $pos;
            if(
$offset >= $i){
               
$i $offset;
               
$result[] = $offset;
            }
        }
    }
    return 
$result;
}
?>

example:-

<?php
$haystack 
"ASD is trying to get out of the ASDs cube but the other ASDs told him that his behavior will destroy the ASDs world";

$needle "ASD";

print_r(strallpos($haystack,$needle));

//getting all the positions starting from a specified position

print_r(strallpos($haystack,$needle,34));
?>
2009-08-11 16:29:19
http://php5.kiev.ua/manual/ru/function.strpos.html
This function raises a warning if the offset is not between 0 and the length of string:

Warning: strpos(): Offset not contained in string in %s on line %d
2009-09-30 23:37:54
http://php5.kiev.ua/manual/ru/function.strpos.html
This function finds postion of nth occurence of a letter starting from offset.

<?php
function nth_position($str$letter$n$offset 0){
   
$str_arr str_split($str);
   
$letter_size array_count_values(str_split(substr($str$offset)));
    if( !isset(
$letter_size[$letter])){
       
trigger_error('letter "' $letter '" does not exist in ' $str ' after ' $offset '. position'E_USER_WARNING);
        return 
false;
    } else if(
$letter_size[$letter] < $n) {
       
trigger_error('letter "' $letter '" does not exist ' $n .' times in ' $str ' after ' $offset '. position'E_USER_WARNING);
        return 
false;
    }
    for(
$i $offset$x 0$count = (count($str_arr) - $offset); $i $count$x != $n$i++){
        if(
$str_arr[$i] == $letter){
           
$x++;
        }
    }
    return 
$i 1;
}

echo 
nth_position('foobarbaz''a'2); //7
echo nth_position('foobarbaz''b'14); //6
?>
2009-10-05 12:05:46
http://php5.kiev.ua/manual/ru/function.strpos.html
Автор:
A function I made to find the first occurrence of a particular needle not enclosed in quotes(single or double). Works for simple nesting (no backslashed nesting allowed).

<?php
function strposq($haystack$needle$offset 0){
   
$len strlen($haystack);
   
$charlen strlen($needle);
   
$flag1 false;
   
$flag2 false;
    for(
$i $offset$i $len$i++){
        if(
substr($haystack$i1) == "'"){
           
$flag1 = !$flag1 && !$flag2 true false;
        }
        if(
substr($haystack$i1) == '"'){
           
$flag2 = !$flag1 && !$flag2 true false;
        }
        if(
substr($haystack$i$charlen) == $needle && !$flag1 && !$flag2){
            return 
$i;       
        }
    }
    return 
false;
}

echo 
strposq("he'llo'character;\"'som\"e;crap"";"); //16
?>
2009-11-06 16:03:34
http://php5.kiev.ua/manual/ru/function.strpos.html
Parse strings between two others in to array.

<?php
function g($string,$start,$end){
     
preg_match_all('/' preg_quote($start'/') . '(.*?)'preg_quote($end'/').'/i'$string$m);
     
$out = array();

     foreach(
$m[1] as $key => $value){
       
$type explode('::',$value);
       if(
sizeof($type)>1){
          if(!
is_array($out[$type[0]]))
             
$out[$type[0]] = array();
         
$out[$type[0]][] = $type[1];
       } else {
         
$out[] = $value;
       }
     }
  return 
$out;
}
print_r(g('Sample text, [/text to extract/] Rest of sample text [/WEB::http://google.com/] bla bla bla. ','[/','/]'));
?>

results:
Array
(
    [0] => text to extract
    [WEB] => Array
        (
            [0] => http://google.com
        )

)

Can be helpfull to custom parsing :)
2010-08-11 08:04:21
http://php5.kiev.ua/manual/ru/function.strpos.html
<?php
$my_array 
= array ('100,101''200,201''300,301');
$check_me_in = array ('100','200','300','400');
foreach (
$check_me_in as $value_cmi){
   
$is_in=FALSE#asume that $check_me_in isn't in $my_array
   
foreach ($my_array as $value_my){
       
$pos strpos($value_my$value_cmi);
        if (
$pos===0)
           
$pos++;
        if (
$pos==TRUE){
           
$is_in=TRUE;
           
$value_my2=$value_my;
            }
    }
    if (
$is_in) echo "ID $value_cmi in \$check_me_in I found in value '$value_my2' \n";
}
?>

The above example will output
ID 100 in $check_me_in I found in value '100,101' 
ID 200 in $check_me_in I found in value '200,201' 
ID 300 in $check_me_in I found in value '300,301'
2010-08-17 18:25:25
http://php5.kiev.ua/manual/ru/function.strpos.html
My version of strpos with needles as an array. Also allows for a string, or an array inside an array.

<?php
function strpos_array($haystack$needles) {
    if ( 
is_array($needles) ) {
        foreach (
$needles as $str) {
            if ( 
is_array($str) ) {
               
$pos strpos_array($haystack$str);
            } else {
               
$pos strpos($haystack$str);
            }
            if (
$pos !== FALSE) {
                return 
$pos;
            }
        }
    } else {
        return 
strpos($haystack$needles);
    }
}

// Test
echo strpos_array('This is a test', array('test''drive')); // Output is 10

?>
2011-03-05 06:44:26
http://php5.kiev.ua/manual/ru/function.strpos.html
A pair of functions to replace every nth occurrence of a string with another string, starting at any position in the haystack. The first works on a string and the second works on a single-level array of strings, treating it as a single string for replacement purposes (any needles split over two array elements are ignored).

Can be used for formatting dynamically-generated HTML output without touching the original generator: e.g. add a newLine class tag to every third item in a floated list, starting with the fourth item.
 
<?php
/* String Replace at Intervals   by Glenn Herbert (gjh42)    2010-12-17
 */
 
//(basic locator by someone else - name unknown)
//strnposr() - Find the position of nth needle in haystack.
function strnposr($haystack$needle$occurrence$pos 0) {
    return (
$occurrence<2)?strpos($haystack$needle$pos):strnposr($haystack,$needle,$occurrence-1,strpos($haystack$needle$pos) + 1);
}

//gjh42
//replace every nth occurrence of $needle with $repl, starting from any position
function str_replace_int($needle$repl$haystack$interval$first=1$pos=0) {
  if (
$pos >= strlen($haystack) or substr_count($haystack$needle$pos) < $first) return $haystack;
 
$firstpos strnposr($haystack$needle$first$pos);
 
$nl strlen($needle);
 
$qty floor(substr_count($haystack$needle$firstpos 1)/$interval);
  do { 
//in reverse order
   
$nextpos strnposr($haystack$needle, ($qty $interval) + 1$firstpos); 
   
$qty--;
   
$haystack substr_replace($haystack$repl$nextpos$nl);
  } while (
$nextpos $firstpos);
  return 
$haystack;
}
 
//$needle = string to find
  //$repl = string to replace needle
  //$haystack = string to do replacing in
  //$interval = number of needles in loop
  //$first=1 = first occurrence of needle to replace (defaults to first) 
  //$pos=0 = position in haystack string to start from (defaults to first) 
 
//replace every nth occurrence of $needle with $repl, starting from any position, in a single-level array
function arr_replace_int($needle$repl$arr$interval$first=1$pos=0$glue='|+|') {
  if (!
is_array($arr))  return $arr;
  foreach(
$arr as $key=>$value){
    if (
is_array($arr[$key])) return $arr;
  }
 
$haystack implode($glue$arr);
 
$haystack str_replace_int($needle$repl$haystack$interval$first$pos);
 
$tarr explode($glue$haystack);
 
$i 0;
  foreach(
$arr as $key=>$value){
   
$arr[$key] = $tarr[$i];
   
$i++;
  }
  return 
$arr;
}
?>
If $arr is not an array, or a multilevel array, it is returned unchanged.
2011-11-07 21:59:18
http://php5.kiev.ua/manual/ru/function.strpos.html
I lost an hour before I noticed that strpos only returns FALSE as a boolean, never TRUE.. This means that

strpos() !== false 

is a different beast then:

strpos() === true

since the latter will never be true. After I found out, The warning in the documentation made a lot more sense.
2012-01-24 09:38:03
http://php5.kiev.ua/manual/ru/function.strpos.html
This is a function I wrote to find all occurrences of a string, using strpos recursively.

<?php
function strpos_recursive($haystack$needle$offset 0, &$results = array()) {               
   
$offset strpos($haystack$needle$offset);
    if(
$offset === false) {
        return 
$results;           
    } else {
       
$results[] = $offset;
        return 
strpos_recursive($haystack$needle, ($offset 1), $results);
    }
}
?>

This is how you use it:

<?php
$string 
'This is some string';
$search 'a';
$found strpos_recursive($string$search);

if(
$found) {
    foreach(
$found as $pos) {
        echo 
'Found "'.$search.'" in string "'.$string.'" at position <b>'.$pos.'</b><br />';
    }   
} else {
    echo 
'"'.$search.'" not found in "'.$string.'"';
}
?>
2012-02-25 17:58:20
http://php5.kiev.ua/manual/ru/function.strpos.html
when you want to know how much of substring occurrences, you'll use "substr_count".
But, retrieve their positions, will be harder.
So, you can do it by starting with the last occurrence :

function strpos_r($haystack, $needle)
{
    if(strlen($needle) > strlen($haystack))
        trigger_error(sprintf("%s: length of argument 2 must be <= argument 1", __FUNCTION__), E_USER_WARNING);

    $seeks = array();
    while($seek = strrpos($haystack, $needle))
    {
        array_push($seeks, $seek);
        $haystack = substr($haystack, 0, $seek);
    }
    return $seeks;
}

it will return an array of all occurrences a the substring in the string

Example : 

$test = "this is a test for testing a test function... blah blah";
var_dump(strpos_r($test, "test"));

// output 

array(3) {
  [0]=>
  int(29)
  [1]=>
  int(19)
  [2]=>
  int(10)
}

Paul-antoine
Malézieux.
2012-04-25 19:46:52
http://php5.kiev.ua/manual/ru/function.strpos.html
Автор:
The most straightforward way to prevent this function from returning 0 is:

  strpos('x'.$haystack, $needle, 1)

The 'x' is simply a garbage character which is only there to move everything 1 position.
The number 1 is there to make sure that this 'x' is ignored in the search.
This way, if $haystack starts with $needle, then the function returns 1 (rather than 0).
2013-02-18 23:55:53
http://php5.kiev.ua/manual/ru/function.strpos.html
Автор:
Don't know if already posted this, but if I did this is an improvement.

This function will check if a string contains  a needle. It _will_ work with arrays and multidimensional arrays (I've tried with a > 16 dimensional array and had no problem).

<?php
function str_contains($haystack$needles)
{
   
//If needles is an array
   
if(is_array($needles))
    {
       
//go trough all the elements
       
foreach($needles as $needle)
        {
           
//if the needle is also an array (ie needles is a multidimensional array)
           
if(is_array($needle))
            {
               
//call this function again
               
if(str_contains($haystack$needle))
                {
                   
//Will break out of loop and function.
                   
return true;
                }
               
                return 
false;
            }

           
//when the needle is NOT an array:
                //Check if haystack contains the needle, will ignore case and check for whole words only
           
elseif(preg_match("/\b$needle\b/i"$haystack) !== 0)
            {
                return 
true;
            }
        }
    }
   
//if $needles is not an array...
   
else
    {
        if(
preg_match("/\b$needles\b/i"$haystack) !== 0)
        {
            return 
true;
        }
    }

    return 
false;
}
?>
2013-12-16 21:02:43
http://php5.kiev.ua/manual/ru/function.strpos.html
This function will return 0 if the string that you are searching matches i.e. needle matches the haystack

{code}
echo strpos('bla', 'bla');
{code}

Output: 0
2014-03-27 18:26:10
http://php5.kiev.ua/manual/ru/function.strpos.html
Be careful when the $haystack or $needle parameter is an integer.
If you are not sure of its type, you should  convert it into a string.
<?php
    var_dump
(strpos(12345,1));//false
   
var_dump(strpos(12345,'1'));//0
   
var_dump(strpos('12345',1));//false
   
var_dump(strpos('12345','1'));//0
   
$a 12345;
   
$b 1;
   
var_dump(strpos(strval($a),strval($b)));//0
   
var_dump(strpos((string)$a,(string)$b));//0   
?>
2014-06-27 13:52:27
http://php5.kiev.ua/manual/ru/function.strpos.html
Автор:
I found a function in this post http://softontherocks.blogspot.com/2014/11/buscar-multiples-textos-en-un-texto-con.html 
that implements the search in both ways, case sensitive or case insensitive, depending on an input parameter.

The function is:

function getMultiPos($haystack, $needles, $sensitive=true, $offset=0){
    foreach($needles as $needle) {
        $result[$needle] = ($sensitive) ? strpos($haystack, $needle, $offset) : stripos($haystack, $needle, $offset);
    }
    return $result;
}

It was very useful for me.
2014-11-04 18:08:52
http://php5.kiev.ua/manual/ru/function.strpos.html
<?php
/*
 * A strpos variant that accepts an array of $needles - or just a string,
 * so that it can be used as a drop-in replacement for the standard strpos,
 * and in which case it simply wraps around strpos and stripos so as not
 * to reduce performance.
 *
 * The "m" in "strposm" indicates that it accepts *m*ultiple needles.
 *
 * Finds the earliest match of *all* needles. Returns the position of this match
 * or false if none found, as does the standard strpos. Optionally also returns
 * via $match either the matching needle as a string (by default) or the index
 * into $needles of the matching needle (if the STRPOSM_MATCH_AS_INDEX flag is
 * set).
 *
 * Case-insensitive searching can be specified via the STRPOSM_CI flag.
 * Note that for case-insensitive searches, if the STRPOSM_MATCH_AS_INDEX is
 * not set, then $match will be in the haystack's case, not the needle's case,
 * unless the STRPOSM_NC flag is also set.
 *
 * Flags can be combined using the bitwise or operator,
 * e.g. $flags = STRPOSM_CI|STRPOSM_NC
 */
define('STRPOSM_CI'            1); // CI => "case insensitive".
define('STRPOSM_NC'            2); // NC => "needle case".
define('STRPOSM_MATCH_AS_INDEX'4);
function 
strposm($haystack$needles$offset 0, &$match null$flags 0) {
   
// In the special case where $needles is not an array, simply wrap
    // strpos and stripos for performance reasons.
   
if (!is_array($needles)) {
       
$func $flags STRPOSM_CI 'stripos' 'strpos';
       
$pos $func($haystack$needles$offset);
        if (
$pos !== false) {
           
$match = (($flags STRPOSM_MATCH_AS_INDEX)
                      ? 
0
                     
: (($flags STRPOSM_NC)
                         ? 
$needles
                         
substr($haystack$posstrlen($needles))
                        )
                      );
            return 
$pos;
        } else    goto 
strposm_no_match;
    }

   
// $needles is an array. Proceed appropriately, initially by...
    // ...escaping regular expression meta characters in the needles.
   
$needles_esc array_map('preg_quote'$needles);
   
// If either of the "needle case" or "match as index" flags are set,
    // then create a sub-match for each escaped needle by enclosing it in
    // parentheses. We use these later to find the index of the matching
    // needle.
   
if (($flags STRPOSM_NC) || ($flags STRPOSM_MATCH_AS_INDEX)) {
       
$needles_esc array_map(
            function(
$needle) {return '('.$needle.')';},
           
$needles_esc
       
);
    }
   
// Create the regular expression pattern to search for all needles.
   
$pattern '('.implode('|'$needles_esc).')';
   
// If the "case insensitive" flag is set, then modify the regular
    // expression with "i", meaning that the match is "caseless".
   
if ($flags STRPOSM_CI$pattern .= 'i';
   
// Find the first match, including its offset.
   
if (preg_match($pattern$haystack$matchesPREG_OFFSET_CAPTURE$offset)) {
       
// Pull the first entry, the overall match, out of the matches array.
       
$found array_shift($matches);
       
// If we need the index of the matching needle, then...
       
if (($flags STRPOSM_NC) || ($flags STRPOSM_MATCH_AS_INDEX)) {
           
// ...find the index of the sub-match that is identical
            // to the overall match that we just pulled out.
            // Because sub-matches are in the same order as needles,
            // this is also the index into $needles of the matching
            // needle.
           
$index array_search($found$matches);
        }
       
// If the "match as index" flag is set, then return in $match
        // the matching needle's index, otherwise...
       
$match = (($flags STRPOSM_MATCH_AS_INDEX)
          ? 
$index
         
// ...if the "needle case" flag is set, then index into
          // $needles using the previously-determined index to return
          // in $match the matching needle in needle case, otherwise...
         
: (($flags STRPOSM_NC)
             ? 
$needles[$index]
             
// ...by default, return in $match the matching needle in
             // haystack case.
             
$found[0]
          )
        );
       
// Return the captured offset.
       
return $found[1];
    }

strposm_no_match:
   
// Nothing matched. Set appropriate return values.
   
$match = ($flags STRPOSM_MATCH_AS_INDEX) ? false null;
    return 
false;
}
?>
2015-04-03 21:02:45
http://php5.kiev.ua/manual/ru/function.strpos.html
It is interesting to be aware of the behavior when the treatment of strings with characters using different encodings.

<?php
# Works like expected. There is no accent
var_dump(strpos("Fabio"'b'));
#int(2)

# The "á" letter is occupying two positions
var_dump(strpos("Fábio"'b')) ;
#int(3)

# Now, encoding the string "Fábio" to utf8, we get some "unexpected" outputs. Every letter that is no in regular ASCII table, will use 4 positions(bytes). The starting point remains like before.
# We cant find the characted, because the haystack string is now encoded.
var_dump(strpos(utf8_encode("Fábio"), 'á'));
#bool(false)

# To get the expected result, we need to encode the needle too
var_dump(strpos(utf8_encode("Fábio"), utf8_encode('á')));
#int(1) 

# And, like said before, "á" occupies 4 positions(bytes)
var_dump(strpos(utf8_encode("Fábio"), 'b'));
#int(5)
2016-02-25 18:58:49
http://php5.kiev.ua/manual/ru/function.strpos.html
Автор:
<?php

/**
 * Find the position of the first occurrence of one or more substrings in a 
 * string.
 * 
 * This function is simulair to function strpos() except that it allows to 
 * search for multiple needles at once.
 *
 * @param string $haystack    The string to search in.
 * @param mixed $needles      Array containing needles or string containing 
 *                            needle.
 * @param integer $offset     If specified, search will start this number of 
 *                            characters counted from the beginning of the 
 *                            string.
 * @param boolean $last       If TRUE then the farthest position from the start 
 *                            of one of the needles is returned.
 *                            If FALSE then the smallest position from start of 
 *                            one of the needles is returned.
 **/
function mstrpos($haystack$needles$offset 0$last false)
{
  if(!
is_array($needles)) { $needles = array($needles); }
 
$found false;
  foreach(
$needles as $needle)
  {
   
$position strpos($haystack, (string)$needle$offset);
    if(
$position === false) { continue; }
   
$exp $last ? ($found === false || $position $found) : 
      (
$found === false || $position $found);
    if(
$exp) { $found $position; }
  }
  return 
$found;
}

/**
 * Find the position of the first (partially) occurrence of a substring in a 
 * string.
 * 
 * This function is simulair to function strpos() except that it wil return a 
 * position when the substring is partially located at the end of the string.
 *
 * @param string $haystack    The string to search in.
 * @param mixed $needle       The needle to search for.
 * @param integer $offset     If specified, search will start this number of 
 *                            characters counted from the beginning of the 
 *                            string.
 **/
function pstrpos($haystack$needle$offset 0)
{
 
$position strpos($haystack$needle$offset);
  if(
$position !== false) { return $position; }
 
  for(
$i strlen($needle); $i 0$i--)
  {
    if(
substr($needle0$i) == substr($haystack, -$i))
    { return 
strlen($haystack) - $i; }
  }
  return 
false;
}

/**
 * Find the position of the first (partially) occurrence of one or more 
 * substrings in a string.
 * 
 * This function is simulair to function strpos() except that it allows to 
 * search for multiple needles at once and it wil return a position when one of
 * the substrings is partially located at the end of the string.
 *
 * @param string $haystack    The string to search in.
 * @param mixed $needles      Array containing needles or string containing 
 *                            needle.
 * @param integer $offset     If specified, search will start this number of 
 *                            characters counted from the beginning of the 
 *                            string.
 * @param boolean $last       If TRUE then the farthest position from the start 
 *                            of one of the needles is returned.
 *                            If FALSE then the smallest position from start of 
 *                            one of the needles is returned.
 **/
function mpstrpos($haystack$needles$offset 0$last false)
{
  if(!
is_array($needles)) { $needles = array($needles); }
 
$found false;
  foreach(
$needles as $needle)
  {
   
$position pstrpos($haystack, (string)$needle$offset);
    if(
$position === false) { continue; }
   
$exp $last ? ($found === false || $position $found) : 
      (
$found === false || $position $found);
    if(
$exp) { $found $position; }
  }
  return 
$found;
}

?>
2016-09-07 01:56:00
http://php5.kiev.ua/manual/ru/function.strpos.html
Docs are missing that WARNING is issued if needle is '' (empty string).

In case of empty haystack it just return false:

For example:

<?php
var_dump
(strpos('foo'''));

var_dump(strpos('''foo'));

var_dump(strpos(''''));
?>

will output:

Warning: strpos(): Empty needle in /in/lADCh on line 3 
bool(false) 

bool(false) 

Warning: strpos(): Empty needle in /in/lADCh on line 7 
bool(false)

Note also that warning text may differ depending on php version, see https://3v4l.org/lADCh
2017-01-23 10:29:48
http://php5.kiev.ua/manual/ru/function.strpos.html
To prevent others from staring at the text, note that the wording of the 'Return Values' section is ambiguous.

Let's say you have a string $myString containing 50 'a's except on position 3 and 43, they contain 'b'.
And for this moment, forget that counting starts from 0.

strpos($myString, 'b', 40) returns 43, great.

And now the text: "Returns the position of where the needle exists relative to the beginning of the haystack string (independent of offset)."

So it doesn't really matter what offset I specify; I'll get the REAL position of the first occurrence in return, which is 3?

... no ...

"independent of offset" means, you will get the REAL positions, thus, not relative to your starting point (offset).

Substract your offset from strpos()'s answer, then you have the position relative to YOUR offset.
2017-04-22 16:16:29
http://php5.kiev.ua/manual/ru/function.strpos.html
Автор:
note that strpos( "8 june 1970"  ,  1970 ) returns FALSE.. 

add quotes to the needle
2017-10-03 12:34:01
http://php5.kiev.ua/manual/ru/function.strpos.html
Warning:
this is not unicode safe

strpos($word,'?') in e?ez-> 1 
strpos($word,'?') in è?ent-> 2
2017-11-27 02:48:15
http://php5.kiev.ua/manual/ru/function.strpos.html
Find position of nth occurrence of a string:

    function strpos_occurrence(string $string, string $needle, int $occurrence, int $offset = null) {
        if((0 < $occurrence) && ($length = strlen($needle))) {
            do {
            } while ((false !== $offset = strpos($string, $needle, $offset)) && --$occurrence && ($offset += $length));
            return $offset;
        }
        return false;
    }
2018-04-19 12:36:46
http://php5.kiev.ua/manual/ru/function.strpos.html
Автор:
This might be useful, I often use for parsing file paths etc.
(Some examples inside https://gist.github.com/msegu/bf7160257037ec3e301e7e9c8b05b00a )
<?php
/**
* Function 'strpos_' finds the position of the first or last occurrence of a substring in a string, ignoring number of characters
*
* Function 'strpos_' is similar to 'str[r]pos()', except:
* 1. fourth (last, optional) param tells, what to return if str[r]pos()===false
* 2. third (optional) param $offset tells as of str[r]pos(), BUT if negative (<0) search starts -$offset characters counted from the end AND skips (ignore!, not as 'strpos' and 'strrpos') -$offset-1 characters from the end AND search backwards
*
* @param string $haystack Where to search
* @param string $needle What to find
* @param int $offset (optional) Number of characters to skip from the beginning (if 0, >0) or from the end (if <0) of $haystack
* @param mixed $resultIfFalse (optional) Result, if not found
*    Example:
*    positive $offset - like strpos:
*        strpos_('abcaba','ab',1)==strpos('abcaba','ab',1)==3, strpos('abcaba','ab',4)===false, strpos_('abcaba','ab',4,'Not found')==='Not found'
*    negative $offset - similar to strrpos:
*        strpos_('abcaba','ab',-1)==strpos('abcaba','ab',-1)==3, strrpos('abcaba','ab',-3)==3 BUT strpos_('abcaba','ab',-3)===0 (omits 2 characters from the end, because -2-1=-3, means search in 'abca'!)
*
* @result int $offset Returns offset (or false), or $resultIfFalse
*/
function strpos_($haystack$needle$offset 0$resultIfFalse false) {
   
$haystack=((string)$haystack);    // (string) to avoid errors with int, float...
   
$needle=((string)$needle);
    if (
$offset>=0) {
       
$offset=strpos($haystack$needle$offset);
        return ((
$offset===false)? $resultIfFalse $offset);
    } else {
       
$haystack=strrev($haystack);
       
$needle=strrev($needle);
       
$offset=strpos($haystack,$needle,-$offset-1);
        return ((
$offset===false)? $resultIfFalse strlen($haystack)-$offset-strlen($needle));
    }
}
?>
2018-07-18 03:41:47
http://php5.kiev.ua/manual/ru/function.strpos.html
Note that strpos() is case sensitive,so when doing a case insensitive search,use stripos() instead..If the latter is not available,subject the string to strlower() first,otherwise you may end up in this situation..
<?php
//say we are matching url routes and calling access control middleware depending on the route

$registered_route '/admin' ;
//now suppose we want to call the authorization middleware before accessing the admin route 
if(strpos($path->url(),$registered_route) === 0){
     
$middleware->call('Auth','login');
}
?>
and the auth middleware is as follows
<?php
class Auth{

function 
login(){
   if(!
loggedIn()){
       return 
redirect("path/to/login.php");
}
return 
true;
}
}

//Now suppose:
$user_url '/admin';
//this will go to the Auth middleware for checks and redirect accordingly

//But:
$user_url '/Admin';
//this will make the strpos function return false since the 'A' in admin is upper case and user will be taken directly to admin dashboard authentication and authorization notwithstanding
?>
Simple fixes:
<?php
//use stripos() as from php 5
if(stripos($path->url(),$registered_route) === 0){
     
$middleware->call('Auth','login');
}
//for those with php 4
if(stripos(strtolower($path->url()),$registered_route) === 0){
     
$middleware->call('Auth','login');
}
//make sure the $registered_route is also lowercase.Or JUST UPGRADE to PHP 5>
2018-09-06 18:00:13
http://php5.kiev.ua/manual/ru/function.strpos.html
Автор:
When a value can be of "unknow" type, I find this conversion trick usefull and more readable than a formal casting (for php7.3+):

<?php
$time 
time();
$string 'This is a test: ' $time;
echo (
strpos($string$time) !== false 'found' 'not found');
echo (
strpos($string"$time") !== false 'found' 'not found');
?>
2019-03-05 19:50:13
http://php5.kiev.ua/manual/ru/function.strpos.html
A more accurate imitation of the PHP function session_start().

Function my_session_start() does something similar to session_start() that has the default configure, and the session files generated by the two are binary compatible.

The code may help people increase their understanding of the principles of the PHP session.

<?php
error_reporting
(E_ALL);
ini_set('display_errors'true);
ini_set('session.save_path'__DIR__);

my_session_start();

echo 
'<p>session id: '.my_session_id().'</p>';

echo 
'<code><pre>';
var_dump($_SESSION);
echo 
'</pre></code>';

$now date('H:i:s');
if (isset(
$_SESSION['last_visit_time'])) {
  echo 
'<p>Last Visit Time: '.$_SESSION['last_visit_time'].'</p>';
}
echo 
'<p>Current Time: '.$now.'</p>';

$_SESSION['last_visit_time'] = $now;

function 
my_session_start() {
  global 
$phpsessid$sessfile;
 
  if (!isset(
$_COOKIE['PHPSESSID']) || empty($_COOKIE['PHPSESSID'])) {
   
$phpsessid my_base32_encode(my_random_bytes(16));
   
setcookie('PHPSESSID'$phpsessidini_get('session.cookie_lifetime'), ini_get('session.cookie_path'), ini_get('session.cookie_domain'), ini_get('session.cookie_secure'), ini_get('session.cookie_httponly'));
  } else {
   
$phpsessid substr(preg_replace('/[^a-z0-9]/'''$_COOKIE['PHPSESSID']), 026);
  }
 
 
$sessfile ini_get('session.save_path').'/sess_'.$phpsessid;
  if (
is_file($sessfile)) {
   
$_SESSION my_unserialize(file_get_contents($sessfile));
  } else {
   
$_SESSION = array();
  }
 
register_shutdown_function('my_session_save');
}

function 
my_session_save() {
  global 
$sessfile;
 
 
file_put_contents($sessfilemy_serialize($_SESSION));
}

function 
my_session_id() {
  global 
$phpsessid;
  return 
$phpsessid;
}

function 
my_serialize($data) {
 
$text '';
  foreach (
$data as $k=>$v) {
   
// key cannot contains '|'
   
if (strpos($k'|') !== false) {
      continue;
    }
   
$text.=$k.'|'.serialize($v)."\n";
  }
  return 
$text;
}

function 
my_unserialize($text) {
 
$data = [];
 
$text explode("\n"$text);
  foreach (
$text as $line) {
   
$pos strpos($line'|');
    if (
$pos === false) {
      continue;
    }
   
$data[substr($line0$pos)] = unserialize(substr($line$pos 1));
  }
  return 
$data;
}

function 
my_random_bytes($length) {
  if (
function_exists('random_bytes')) {
      return 
random_bytes($length);
  }
 
$randomString '';
  for (
$i 0$i $length$i++) { 
     
$randomString .= chr(rand(0255));
  } 
  return 
$randomString;
}

function 
my_base32_encode($input) {
 
$BASE32_ALPHABET 'abcdefghijklmnopqrstuvwxyz234567';
 
$output '';
 
$v 0;
 
$vbits 0;
  for (
$i 0$j strlen($input); $i $j$i++) {
   
$v <<= 8;
   
$v += ord($input[$i]);
   
$vbits += 8;
    while (
$vbits >= 5) {
     
$vbits -= 5;
     
$output .= $BASE32_ALPHABET[$v >> $vbits];
     
$v &= ((<< $vbits) - 1);
    }
  }
  if (
$vbits 0) {
   
$v <<= ($vbits);
   
$output .= $BASE32_ALPHABET[$v];
  }
  return 
$output;
}
2019-06-09 16:25:42
http://php5.kiev.ua/manual/ru/function.strpos.html
Note this code example below in PHP 7.3
<?php
$str 
"17,25";

if(
FALSE !== strpos($str25)){
    echo 
"25 is inside of str";
} else {
    echo 
"25 is NOT inside of str";
}
?>

Will output "25 is NOT inside of str" and will throw out a deprication message, that non string needles will be interpreted as strings in the future.

This just gave me some headache since the value I am checking against comes from the database as an integer.
2020-01-03 11:35:55
http://php5.kiev.ua/manual/ru/function.strpos.html
To check that a substring is present.

Confusing check if position is not false:

if ( strpos ( $haystack , $needle ) !== FALSE )

Logical check if there is position:

if ( is_int ( strpos ( $haystack , $needle ) ) )
2020-11-23 12:14:30
http://php5.kiev.ua/manual/ru/function.strpos.html

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