Как найти позицию символа в строке php

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.

<?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.'"';
}
?>

<?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)

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.

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.

    for(

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

strpos($word,'?') in e?ez-> 1
strpos($word,'?') in è?ent-> 2

<?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 :)

<?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?>

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.

<?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

?>

<?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', 1, 4); //6
?>

<?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);
}
?>

<?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');
?>

  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).

    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;
    }

Warning: strpos(): Offset not contained in string in %s on line %d

<?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, $i, 1) == "'"){

            $flag1 = !$flag1 && !$flag2 ? true : false;

        }

        if(substr($haystack, $i, 1) == '"'){

            $flag2 = !$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

?>

<?phpfunction 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;
    }
    //
}?>

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.

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$needleb/i", $haystack) !== 0)
            {
                return true;
            }
        }
    }
    //if $needles is not an array...
    else
    {
        if(preg_match("/b$needlesb/i", $haystack) !== 0)
        {
            return true;
        }
    }

    return

false;
}
?>

<?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));

?>

<?php

//instr function to mimic vb instr fucntion

function InStr($haystack, $needle)

{

    $pos=strpos($haystack, $needle);

    if ($pos !== false)

    {

        return $pos;

    }

    else

    {

        return -1;

    }

}

?>

<?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;

    }

}

?>

<?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==0 || $L2==0 ) {
        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;
}
?>

add quotes to the needle

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.

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:

if(

FALSE !== strpos($str, 25)){
    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.

Confusing check if position is not false:

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

Logical check if there is position:

if ( is_int ( strpos ( $haystack , $needle ) ) )

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

Output: 0

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', $phpsessid, ini_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]/', '', $_COOKIE['PHPSESSID']), 0, 26);
  }$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 $sessfile;file_put_contents($sessfile, my_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;
    }
    $data[substr($line, 0, $pos)] = unserialize(substr($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(0, 255));
  }
  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 &= ((1 << $vbits) - 1);
    }
  }
  if ($vbits > 0) {
    $v <<= (5 - $vbits);
    $output .= $BASE32_ALPHABET[$v];
  }
  return $output;
}