(PHP 4, PHP 5, PHP 7, PHP 8)
strpos — Find the position of the first occurrence of a substring in a string
Description
strpos(string $haystack
, string $needle
, int $offset
= 0): int|false
Parameters
-
haystack
-
The string to search in.
-
needle
-
Prior to PHP 8.0.0, if
needle
is not a string, it is converted
to an integer and applied as the ordinal value of a character.
This behavior is deprecated as of PHP 7.3.0, and relying on it is highly
discouraged. Depending on the intended behavior, the
needle
should either be explicitly cast to string,
or an explicit call to chr() should be performed. -
offset
-
If specified, search will start this number of characters counted from
the beginning of the string. If the offset is negative, the search will start
this number of characters counted from the end of the string.
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.
Changelog
Version | Description |
---|---|
8.0.0 |
Passing an int as needle is no longer supported.
|
7.3.0 |
Passing an int as needle has been deprecated.
|
7.1.0 |
Support for negative offset s has been added.
|
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); // $pos = 7, not 0
?>
Notes
Note: This function is
binary-safe.
See Also
- stripos() – Find the position of the first occurrence of a case-insensitive substring in a string
- str_contains() – Determine if a string contains a given substring
- str_ends_with() – Checks if a string ends with a given substring
- str_starts_with() – Checks if a string starts with a given substring
- strrpos() – Find the position of the last occurrence of a substring in a string
- strripos() – Find the position of the last occurrence of a case-insensitive substring in a string
- strstr() – Find the first occurrence of a string
- strpbrk() – Search a string for any of a set of characters
- substr() – Return part of a string
- preg_match() – Perform a regular expression match
Suggested re-write for pink WARNING box ¶
15 years ago
WARNING
As strpos may return either FALSE (substring absent) or 0 (substring at start of string), strict versus loose equivalency operators must be used very carefully.
To know that a substring is absent, you must use:
=== FALSE
To know that a substring is present (in any position including 0), you can use either of:
!== FALSE (recommended)
> -1 (note: or greater than any negative number)
To know that a substring is at the start of the string, you must use:
=== 0
To know that a substring is in any position other than the start, you can use any of:
> 0 (recommended)
!= 0 (note: but not !== 0 which also equates to FALSE)
!= FALSE (disrecommended as highly confusing)
Also note that you cannot compare a value of "" to the returned value of strpos. With a loose equivalence operator (== or !=) it will return results which don't distinguish between the substring's presence versus position. With a strict equivalence operator (=== or !==) it will always return false.
martijn at martijnfrazer dot nl ¶
11 years ago
This is a function I wrote to find all occurrences of a string, using strpos recursively.
<?php
function strpos_recursive($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.'"';
}
?>
fabio at naoimporta dot com ¶
7 years ago
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)
mtroy dot student at gmail dot com ¶
11 years ago
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.
rjeggens at ijskoud dot org ¶
11 years ago
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.
m.m.j.kronenburg ¶
6 years ago
<?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; $i--)
{
if(substr($needle, 0, $i) == substr($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 $found;
}?>
jexy dot ru at gmail dot com ¶
6 years ago
Docs are missing that WARNING is issued if needle is '' (empty string).
In case of empty haystack it just return false:
For example:
<?php
var_dump(strpos('foo', ''));var_dump(strpos('', 'foo'));var_dump(strpos('', ''));
?>
will output:
Warning: strpos(): Empty needle in /in/lADCh on line 3
bool(false)
bool(false)
Warning: strpos(): Empty needle in /in/lADCh on line 7
bool(false)
Note also that warning text may differ depending on php version, see https://3v4l.org/lADCh
greg at spotx dot net ¶
5 years ago
Warning:
this is not unicode safe
strpos($word,'?') in e?ez-> 1
strpos($word,'?') in è?ent-> 2
usulaco at gmail dot com ¶
12 years ago
Parse strings between two others in to array.
<?php
function g($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 $out;
}
print_r(g('Sample text, [/text to extract/] Rest of sample text [/WEB::http://google.com/] bla bla bla. ','[/','/]'));
?>
results:
Array
(
[0] => text to extract
[WEB] => Array
(
[0] => http://google.com
)
)
Can be helpfull to custom parsing :)
akarmenia at gmail dot com ¶
12 years ago
My version of strpos with needles as an array. Also allows for a string, or an array inside an array.
<?php
function strpos_array($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?>
eef dot vreeland at gmail dot com ¶
6 years ago
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.
ohcc at 163 dot com ¶
8 years ago
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
?>
ilaymyhat-rem0ve at yahoo dot com ¶
15 years ago
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 $result;
}
}
//String
?>
yasindagli at gmail dot com ¶
13 years ago
This function finds postion of nth occurence of a letter starting from offset.
<?php
function nth_position($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 $i - 1;
}
echo
nth_position('foobarbaz', 'a', 2); //7
echo nth_position('foobarbaz', 'b', 1, 4); //6
?>
bishop ¶
19 years ago
Code like this:
<?php
if (strpos('this is a test', 'is') !== false) {
echo "found it";
}
?>
gets repetitive, is not very self-explanatory, and most people handle it incorrectly anyway. Make your life easier:
<?php
function str_contains($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);
}
?>
Jean ¶
4 years ago
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, "$time") !== false ? 'found' : 'not found');
?>
Anonymous ¶
10 years ago
The most straightforward way to prevent this function from returning 0 is:
strpos('x'.$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).
marvin_elia at web dot de ¶
5 years ago
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 $offset;
}
return false;
}
digitalpbk [at] gmail.com ¶
13 years ago
This function raises a warning if the offset is not between 0 and the length of string:
Warning: strpos(): Offset not contained in string in %s on line %d
Achintya ¶
13 years ago
A function I made to find the first occurrence of a particular needle not enclosed in quotes(single or double). Works for simple nesting (no backslashed nesting allowed).
<?php
function strposq($haystack, $needle, $offset = 0){
$len = strlen($haystack);
$charlen = strlen($needle);
$flag1 = false;
$flag2 = false;
for($i = $offset; $i < $len; $i++){
if(substr($haystack, $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 $i;
}
}
return false;
}
echo
strposq("he'llo'character;"'som"e;crap", ";"); //16
?>
spinicrus at gmail dot com ¶
16 years ago
if you want to get the position of a substring relative to a substring of your string, BUT in REVERSE way:
<?phpfunction strpos_reverse_way($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;
}
//
}?>
lairdshaw at yahoo dot com dot au ¶
8 years ago
<?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, $pos, strlen($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, $matches, PREG_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;
}
?>
qrworld.net ¶
8 years ago
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 $result;
}
It was very useful for me.
Lurvik ¶
9 years ago
Don't know if already posted this, but if I did this is an improvement.
This function will check if a string contains a needle. It _will_ work with arrays and multidimensional arrays (I've tried with a > 16 dimensional array and had no problem).
<?php
function str_contains($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, $needle))
{
//Will break out of loop and function.
return true;
}
return
false;
}//when the needle is NOT an array:
//Check if haystack contains the needle, will ignore case and check for whole words only
elseif(preg_match("/b$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;
}
?>
gambajaja at yahoo dot com ¶
12 years ago
<?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 $check_me_in I found in value '300,301'
ah dot d at hotmail dot com ¶
13 years ago
A strpos modification to return an array of all the positions of a needle in the haystack
<?php
function strallpos($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,$needle,34));
?>
teddanzig at yahoo dot com ¶
14 years ago
routine to return -1 if there is no match for strpos
<?php
//instr function to mimic vb instr fucntion
function InStr($haystack, $needle)
{
$pos=strpos($haystack, $needle);
if ($pos !== false)
{
return $pos;
}
else
{
return -1;
}
}
?>
Tim ¶
14 years ago
If you would like to find all occurences of a needle inside a haystack you could use this function strposall($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 $aStrPos;
}
else {
return false;
}
}
?>
user at nomail dot com ¶
16 years ago
This is a bit more useful when scanning a large string for all occurances between 'tags'.
<?php
function getStrsBetween($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==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
$result;
}
?>
philip ¶
18 years ago
Many people look for in_string which does not exist in PHP, so, here's the most efficient form of in_string() (that works in both PHP 4/5) that I can think of:
<?php
function in_string($needle, $haystack, $insensitive = false) {
if ($insensitive) {
return false !== stristr($haystack, $needle);
} else {
return false !== strpos($haystack, $needle);
}
}
?>
Lhenry ¶
5 years ago
note that strpos( "8 june 1970" , 1970 ) returns FALSE..
add quotes to the needle
gjh42 – simonokewode at hotmail dot com ¶
11 years ago
A pair of functions to replace every nth occurrence of a string with another string, starting at any position in the haystack. The first works on a string and the second works on a single-level array of strings, treating it as a single string for replacement purposes (any needles split over two array elements are ignored).
Can be used for formatting dynamically-generated HTML output without touching the original generator: e.g. add a newLine class tag to every third item in a floated list, starting with the fourth item.
<?php
/* String Replace at Intervals by Glenn Herbert (gjh42) 2010-12-17
*/
//(basic locator by someone else - name unknown)
//strnposr() - Find the position of nth needle in haystack.
function strnposr($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 $arr is not an array, or a multilevel array, it is returned unchanged.
amolocaleb at gmail dot com ¶
4 years ago
Note that strpos() is case sensitive,so when doing a case insensitive search,use stripos() instead..If the latter is not available,subject the string to strlower() first,otherwise you may end up in this situation..
<?php
//say we are matching url routes and calling access control middleware depending on the route$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>
ds at kala-it dot de ¶
3 years ago
Note this code example below in PHP 7.3
<?php
$str = "17,25";
if(
FALSE !== strpos($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.
sunmacet at gmail dot com ¶
2 years ago
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 , $needle ) ) )
binodluitel at hotmail dot com ¶
9 years ago
This function will return 0 if the string that you are searching matches i.e. needle matches the haystack
{code}
echo strpos('bla', 'bla');
{code}
Output: 0
hu60 dot cn at gmail dot com ¶
3 years ago
A more accurate imitation of the PHP function session_start().
Function my_session_start() does something similar to session_start() that has the default configure, and the session files generated by the two are binary compatible.
The code may help people increase their understanding of the principles of the PHP session.
<?php
error_reporting(E_ALL);
ini_set('display_errors', true);
ini_set('session.save_path', __DIR__);my_session_start();
echo
'<p>session id: '.my_session_id().'</p>';
echo
'<code><pre>';
var_dump($_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', $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;
}
msegit post pl ¶
4 years ago
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));
}
}
?>
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A string is a collection of given characters and a substring is a string present in a given string.
In this article, we are going to check if the given string contains a substring by using the PHP strpos() function.
Syntax:
strpos($original_string,$sub_string);
Parameters:
- original_string : The input string
- sub_string : The substring searched in the original input string.
Return type: Boolean value
- True, If substring found
- False, If substring not found.
Example:
PHP
<?php
$input_string
=
"sravan kumar author at geeks for geeks "
;
$sub
=
"geeks"
;
if
(
strpos
(
$input_string
,
$sub
) !== false)
{
echo
"True"
;
}
else
{
echo
"False"
;
}
?>
Output:
True
Example 2:
PHP
<?php
$input_string
=
"sravan kumar author at geeks for geeks "
;
$sub
=
"computer"
;
if
(
strpos
(
$input_string
,
$sub
) !== false)
{
echo
"True"
;
}
else
{
echo
"False"
;
}
?>
Output:
False
Example 3: The following example also considers space.
PHP
<?php
$input_string
=
"geeks for geeks java python php"
;
$sub
=
" "
;
if
(
strpos
(
$input_string
,
$sub
) !== false)
{
echo
"True"
;
}
else
{
echo
"False"
;
}
?>
Output:
True
Example 4:
PHP
<?php
$input_string
=
"geeks for geeks java python php"
;
$sub
=
" dbms"
;
if
(
strpos
(
$input_string
,
$sub
) !== false)
{
echo
"True"
;
}
else
{
echo
"False"
;
}
?>
Output:
False
Last Updated :
30 Apr, 2021
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За последние 24 часа нас посетили 12600 программистов и 1101 робот. Сейчас ищут 555 программистов …
strpos
(PHP 4, PHP 5, PHP 7)
strpos — Возвращает позицию первого вхождения подстроки
Описание
mixed strpos
( string $haystack
, mixed $needle
[, int $offset
= 0
] )
Список параметров
-
haystack
-
Строка, в которой производится поиск
-
needle
-
Если
needle
не является строкой, он приводится
к целому и трактуется как код символа. -
offset
-
Если этот параметр указан, то поиск будет начат с указанного количества символов с начала строки. В отличии от strrpos() и
strripos() данный параметр не может быть отрицательным.
Возвращаемые значения
Возвращает позицию, в которой находится искомая строка, относительно
начала строки haystack
(независимо от смещения (offset).
Также обратите внимание на то, что позиция строки отсчитывается от 0, а не от 1.
Возвращает FALSE
, если искомая строка не найдена.
Внимание
Эта функция
может возвращать как boolean FALSE
, так и не-boolean значение,
которое приводится к FALSE
. За более подробной информацией обратитесь к разделу
Булев тип. Используйте оператор === для проверки значения,
возвращаемого этой функцией.
Примеры
Пример #1 Использование ===
<?php
$mystring = 'abc';
$findme = 'a';
$pos = strpos($mystring, $findme);// Заметьте, что используется ===. Использование == не даст верного
// результата, так как 'a' находится в нулевой позиции.
if ($pos === false) {
echo "Строка '$findme' не найдена в строке '$mystring'";
} else {
echo "Строка '$findme' найдена в строке '$mystring'";
echo " в позиции $pos";
}
?>
Пример #2 Использование !==
<?php
$mystring = 'abc';
$findme = 'a';
$pos = strpos($mystring, $findme);// Оператор !== также можно использовать. Использование != не даст верного
// результата, так как 'a' находится в нулевой позиции. Выражение (0 != false) приводится
// к false.
if ($pos !== false) {
echo "Строка '$findme' найдена в строке '$mystring'";
echo " в позиции $pos";
} else {
echo "Строка '$findme' не найдена в строке '$mystring'";
}
?>
Пример #3 Использование смещения
<?php
// Можно искать символ, игнорируя символы до определенного смещения
$newstring = 'abcdef abcdef';
$pos = strpos($newstring, 'a', 1); // $pos = 7, не 0
?>
Примечания
Замечание: Эта функция безопасна
для обработки данных в двоичной форме.
Смотрите также
- stripos() – Возвращает позицию первого вхождения подстроки без учета регистра
- strrpos() – Возвращает позицию последнего вхождения подстроки в строке
- strripos() – Возвращает позицию последнего вхождения подстроки без учета регистра
- strstr() – Находит первое вхождение подстроки
- strpbrk() – Ищет в строке любой символ из заданного набора
- substr() – Возвращает подстроку
- preg_match() – Выполняет проверку на соответствие регулярному выражению
Вернуться к: Обработка строк
Теги: php, поиск, строка, подстрока, найти
В некоторых случаях возникает необходимость найти подстроку в строке, используя встроенные возможности языка программирования PHP. Чтобы решить эту задачу, можно использовать разные инструменты.
Поиск подстроки в строке с помощью strpos
В PHP есть функция под названием strpos, возвращающая позицию 1-го вхождения символа подстроки. Давайте рассмотрим небольшой пример её работы:
$mystring = 'abc'; $findme = 'a'; $pos = strpos($mystring, $findme); // Обратите внимание, что применяется ===. Применение == не даст нам верного // результата, т. к. 'a' находится в нулевой позиции. if ($pos === false) { echo "Строка '$findme' не найдена в строке '$mystring'"; } else { echo "Строка '$findme' найдена в строке '$mystring'"; echo " в позиции $pos"; }Таким образом, PHP-функция возвращает нам или порядковый номер 1-го символа подстроки в исходной строке, или false, если ничего не найдено.
Применяя эту функцию, учтите, что она может вернуть вам в качестве результата 0 — в таком случае можно говорить, что подстрока находится в самом начале нашей исходной строки. Именно поэтому следует применять троекратный знак равно, о котором упомянуто в коде ($pos === false). Это нужно для проверки успешности поиска.
Поиск подстроки в строке с помощью stripos
Эта функция является регистронезависимым аналогом strpos. Она пригодится, если захотите найти последнее вхождение подстроки. Кстати, регистронезависимый вариант есть и у неё — strripos.
Используем для поиска PHP-функцию preg_match
Данная функция позволит выполнить поиск подстроки, задействуя регулярное выражение. Напомним, что регулярное выражение представляет собой шаблон, сравниваемый со строкой. При этом под один шаблон порой подходят сразу много разных строк.
Регулярные выражения пригодятся, если надо выполнять поиск и проверку не по конкретной подстроке, а требуется обнаружить все строки, которые обладают свойствами, описанными посредством регулярных выражений. Вообще, по правде говоря, знание данной темы заметно расширит ваши возможности и облегчит работу со строками.
Выполним проверку:
$html = 'content <title>hello php!</title> content'; if (preg_match("!<title>(.*?)</title>!si", $html, $matches)){ echo $matches[1]; } else { echo "Тег не был найден"; }Остаётся добавить, что язык программирования PHP располагает богатейшим выбором функций для работы с регулярными выражениями. Это раз. Что касается нашей основной темы, то нельзя не сказать, что для работы со строками в PHP тоже есть огромное количество функций, знакомиться с которыми лучше в официальной документации.
Если же хотите прокачать свои навыки PHP-разработки под руководством практикующих экспертов, добро пожаловать на специальный курс в OTUS!
You could use regular expressions as it’s better for word matching compared to strpos
, as mentioned by other users. A strpos
check for are
will also return true for strings such as: fare, care, stare, etc. These unintended matches can simply be avoided in regular expression by using word boundaries.
A simple match for are
could look something like this:
$a = 'How are you?';
if (preg_match('/bareb/', $a)) {
echo 'true';
}
On the performance side, strpos
is about three times faster. When I did one million compares at once, it took preg_match
1.5 seconds to finish and for strpos
it took 0.5 seconds.
Edit:
In order to search any part of the string, not just word by word, I would recommend using a regular expression like
$a = 'How are you?';
$search = 'are y';
if(preg_match("/{$search}/i", $a)) {
echo 'true';
}
The i
at the end of regular expression changes regular expression to be case-insensitive, if you do not want that, you can leave it out.
Now, this can be quite problematic in some cases as the $search string isn’t sanitized in any way, I mean, it might not pass the check in some cases as if $search
is a user input they can add some string that might behave like some different regular expression…
Also, here’s a great tool for testing and seeing explanations of various regular expressions Regex101
To combine both sets of functionality into a single multi-purpose function (including with selectable case sensitivity), you could use something like this:
function FindString($needle,$haystack,$i,$word)
{ // $i should be "" or "i" for case insensitive
if (strtoupper($word)=="W")
{ // if $word is "W" then word search instead of string in string search.
if (preg_match("/b{$needle}b/{$i}", $haystack))
{
return true;
}
}
else
{
if(preg_match("/{$needle}/{$i}", $haystack))
{
return true;
}
}
return false;
// Put quotes around true and false above to return them as strings instead of as bools/ints.
}
One more thing to take in mind, is that b
will not work in different languages other than english.
The explanation for this and the solution is taken from here:
b
represents the beginning or end of a word (Word Boundary). This
regex would match apple in an apple pie, but wouldn’t match apple in
pineapple, applecarts or bakeapples.How about “café”? How can we extract the word “café” in regex?
Actually, bcaféb wouldn’t work. Why? Because “café” contains
non-ASCII character: é. b can’t be simply used with Unicode such as
समुद्र, 감사, месяц and 😉 .When you want to extract Unicode characters, you should directly
define characters which represent word boundaries.The answer:
(?<=[s,.:;"']|^)UNICODE_WORD(?=[s,.:;"']|$)
So in order to use the answer in PHP, you can use this function:
function contains($str, array $arr) {
// Works in Hebrew and any other unicode characters
// Thanks https://medium.com/@shiba1014/regex-word-boundaries-with-unicode-207794f6e7ed
// Thanks https://www.phpliveregex.com/
if (preg_match('/(?<=[s,.:;"']|^)' . $word . '(?=[s,.:;"']|$)/', $str)) return true;
}
And if you want to search for array of words, you can use this:
function arrayContainsWord($str, array $arr)
{
foreach ($arr as $word) {
// Works in Hebrew and any other unicode characters
// Thanks https://medium.com/@shiba1014/regex-word-boundaries-with-unicode-207794f6e7ed
// Thanks https://www.phpliveregex.com/
if (preg_match('/(?<=[s,.:;"']|^)' . $word . '(?=[s,.:;"']|$)/', $str)) return true;
}
return false;
}
As of PHP 8.0.0 you can now use str_contains
<?php
if (str_contains('abc', '')) {
echo "Checking the existence of the empty string will always"
return true;
}