(PHP 4, PHP 5)
strpos — 查找字符串首次出现的位置
返回 needle 在 haystack 中首次出现的数字位置。与 strrpos() 不同，在 PHP 5 之前，该函数可以使用一个完整字符串作为 needle，并且整个字符串都将被使用。
haystack
在该字符串中进行查找。
needle
如果 needle 不是一个字符串，那么它将被转换为整型并被视为字符的顺序值。
offset
可选的 offset 参数可以用来指定从 haystack 中的哪一个字符开始查找。返回的数字位置是相对于 haystack 的起始位置而言的。
以整型返回位置信息。如果没找到 needle， strpos() 将返回布尔型的 FALSE 值。
Example #1 使用 ===
<?php
$mystring = 'abc';
$findme = 'a';
$pos = strpos($mystring, $findme);
// 注意这里使用的是 ===。简单的 == 不能像我们期待的那样工作，
// 因为 'a' 是第 0 位置上的（第一个）字符。
if ($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 使用 !==
<?php
$mystring = 'abc';
$findme = 'a';
$pos = strpos($mystring, $findme);
// 使用 !== 操作符。使用 != 不能像我们期待的那样工作，
// 因为 'a' 的位置是 0。语句 (0 != false) 的结果是 false。
if ($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 使用位置偏移量
<?php
// 忽视位置偏移量之前的字符进行查找
$newstring = 'abcdef abcdef';
$pos = strpos($newstring, 'a', 1); // $pos = 7, 不是 0
?>
Note: 此函数可安全用于二进制对象。
Anonymous (2013-02-18 21:55:53)
The most straightforward way to prevent this function from returning 0 is:
strpos('x'.$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).
Aleksey Korzun (2012-10-24 19:07:08)
Just a quick note, if by some chance you pass an array to strpos function you might have unexpected behaviour.
<?php
$foobar = array();
if(strpos($foobar, 'something') !== false) {
}
?>
The above condition will actually pass and execute your code.
Anonymous (2012-10-06 05:53:19)
There is a more efficient way when looking for the position of each occurrence:
<?php
while($count = strpos($input1, $input2, $count+1))
$output[] = $count+1;
?>
Use the offset value, then you don't spend a ton of time re-writing the value into memory
mtroy dot student at gmail dot com (2012-04-25 16:46:52)
when you want to know how much of substring occurrences, you'll use "substr_count".
But, retrieve their positions, will be harder.
So, you can do it by starting with the last occurrence :
function strpos_r($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.
martijn at martijnfrazer dot nl (2012-02-25 15:58:20)
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.'"';
}
?>
rjeggens at ijskoud dot org (2012-01-24 07:38:03)
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.
gjh42 - simonokewode at hotmail dot com (2011-11-07 19:59:18)
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.
Mark Oates (2011-10-25 20:36:17)
When using GLOB_BRACE to find files on a local computer, note that including the drive lettername within the braces may cause the behavior to not work as expected:
<?php
$location = "{c:/foo/*.txt,c:/foo/bar/*.txt}"; // < will NOT work
$location = "c:{/foo/*.txt,/foo/bar/*.txt}"; // < works
$location = "c:/{foo/*.txt,foo/bar/*.txt}"; // < works
$location = "{/foo/*.txt,/foo/bar/*.txt}"; // < works
print_r(glob($location, GLOB_BRACE));
?>
jim at terrys dot net (2011-09-29 23:53:55)
strpos that accepts an array for $needle
<?php
// strpos that takes an array of values to match against a string
// note the stupid argument order (to match strpos)
function strpos_arr($haystack, $needle) {
if(!is_array($needle)) $needle = array($needle);
foreach($needle as $what) {
if(($pos = strpos($haystack, $what))!==false) return $pos;
}
return false;
}
?>
----------------------------
http://www.show-ip.org
a at bc dot de (2011-06-23 08:32:57)
A simple way to get the FIRST occurence of any $needle.
Needed if more than one $needle could occur in $haystack and you want the first occurence of any $needle.
<?php
function strpos_arr($haystack, $needle) {
$First = strlen($haystack);
if(!is_array($needle)) $needle = array($needle);
foreach($needle as $what) {
$pos = strpos($haystack, $what);
if($pos !== false)
{
if($pos < $First) $First = $pos;
}
}
return $First == strlen($haystack) ? false : $First;
}
?>
akarmenia at gmail dot com (2011-03-05 04:44:26)
My version of strpos with needles as an array. Also allows for a string, or an array inside an array.
<?php
function strpos_array($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
?>
jaimthorn at yahoo dot com (2011-02-09 02:09:20)
A complete set of strn*pos functions that look for the nth occurrence of the needle in the haystack. I prefer this implementation of strnpos because it doesn't give visible warnings when supplied with a needle of length 0 (which is, admittedly, non-standard behavior). Based on a version I [originally posted on 05-MAR-2010]; this new version conforms more to the semantics of strpos.
<?php
/**
* This function implements all the strn*pos functions, which return the $nth occurrence of $needle
* in $haystack, or false if it doesn't exist / when illegal parameters have been supplied.
*
* @param string $haystack the string to search in.
* @param MIXED $needle the string or the ASCII value of the character to search for.
* @param integer $nth the number of the occurrence to look for.
* @param integer $offset the position in $haystack to start looking for $needle.
* @param bool $insensitive should the function be case insensitive?
* @param bool $reverse should the function work its way backwards in the haystack?
* @return MIXED integer either the position of the $nth occurrence of $needle in $haystack,
* or boolean false if it can't be found.
*/
function strnripos_generic( $haystack, $needle, $nth, $offset, $insensitive, $reverse )
{
// If needle is not a string, it is converted to an integer and applied as the ordinal value of a character.
if( ! is_string( $needle ) ) {
$needle = chr( (int) $needle );
}
// Are the supplied values valid / reasonable?
$len = strlen( $needle );
if( 1 > $nth || 0 === $len ) {
return false;
}
if( $insensitive ) {
$haystack = strtolower( $haystack );
$needle = strtolower( $needle );
}
if( $reverse ) {
$haystack = strrev( $haystack );
$needle = strrev( $needle );
}
// $offset is incremented in the call to strpos, so make sure that the first
// call starts at the right position by initially decreasing $offset by $len.
$offset -= $len;
do
{
$offset = strpos( $haystack, $needle, $offset + $len );
} while( --$nth && false !== $offset );
return false === $offset || ! $reverse ? $offset : strlen( $haystack ) - $offset;
}
/**
* @see strnripos_generic
*/
function strnpos( $haystack, $needle, $nth, $offset = 0 )
{
return strnripos_generic( $haystack, $needle, $nth, $offset, false, false );
}
/**
* @see strnripos_generic
*/
function strnipos( $haystack, $needle, $nth, $offset = 0 )
{
return strnripos_generic( $haystack, $needle, $nth, $offset, true, false );
}
/**
* @see strnripos_generic
*/
function strnrpos( $haystack, $needle, $nth, $offset = 0 )
{
return strnripos_generic( $haystack, $needle, $nth, $offset, false, true );
}
/**
* @see strnripos_generic
*/
function strnripos( $haystack, $needle, $nth, $offset = 0 )
{
return strnripos_generic( $haystack, $needle, $nth, $offset, true, true );
}
$haystack = 'Dit is een HoTtentotTentenTentenToonstellingTest!';
echo strnpos ( $haystack, 't', 5 ), ' === ', strnpos ( $haystack, 116, 5 ), PHP_EOL;
echo strnipos ( $haystack, 't', 5 ), ' === ', strnipos ( $haystack, 116, 5 ), PHP_EOL;
echo strnrpos ( $haystack, 't', 5 ), ' === ', strnrpos ( $haystack, 116, 5 ), PHP_EOL;
echo strnripos( $haystack, 't', 5 ), ' === ', strnripos( $haystack, 116, 5 ), PHP_EOL;
echo PHP_EOL;
echo strnpos ( $haystack, 'T', 5 ), ' === ', strnpos ( $haystack, 84, 5 ), PHP_EOL;
echo strnipos ( $haystack, 'T', 5 ), ' === ', strnipos ( $haystack, 84, 5 ), PHP_EOL;
echo strnrpos ( $haystack, 'T', 5 ), ' === ', strnrpos ( $haystack, 84, 5 ), PHP_EOL;
echo strnripos( $haystack, 'T', 5 ), ' === ', strnripos( $haystack, 84, 5 ), PHP_EOL;
?>
Anonymous (2010-08-19 02:50:30)
beware the mindless "if needle is not string" :
root@voice1:/www/voice_ed#php -r 'var_dump(strpos("X1234567",5));'
bool(false)
root@voice1:/www/voice_ed#php -r 'var_dump(strpos("X1234567","5"));'
int(5)
root@voice1:/www/voice_ed#
gambajaja at yahoo dot com (2010-08-17 15:25:25)
<?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 $check_me_in I found in value '300,301'
usulaco at gmail dot com (2010-08-11 05:04:21)
Parse strings between two others in to array.
<?php
function g($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 :)
james [at] bandit co.nz (2010-05-28 04:38:34)
strpos that accepts an array for $needle
<?php
// strpos that takes an array of values to match against a string
// note the stupid argument order (to match strpos)
function strpos_arr($haystack, $needle) {
if(!is_array($needle)) $needle = array($needle);
foreach($needle as $what) {
if(($pos = strpos($haystack, $what))!==false) return $pos;
}
return false;
}
?>
olmstead31 at yahoo dot com (2010-03-23 07:48:28)
I found that whatever I was using as a test with strpos it came out false exept if $pos was == 1
I figured it gives me a numeric value if found else it is null or false
here is what i did to make my code work:
<?php
//EXAMPLE 1:
$quiamime = ',64,68,70,';
$me = '64'
$posi = strpos($quiaime, ",$me,"); //posi is equal to 0
if (!is_numeric($posi)){
//code here
}else{
//else code here
}
//EXAMPLE 2:
$quiamime = ',68,70,64,';
$me = '64'
$posi = strpos($quiaime, ",$me,"); //posi is equal to 6
if (!is_numeric($posi)){
//code here
}else{
//else code here
}
//EXAMPLE 3:
$quiamime = ',68,70,';
$me = '64'
$posi = strpos($quiaime, ",$me,"); //posi is equal to NULL or FALSE
if (!is_numeric($posi)){
//code here
}else{
//else code here
}
?>
daevid at daevid dot com (2010-01-26 14:46:13)
Dan Brown and I had a discussion on the PHP list about the speed difference between the popular three string searching techniques. He wrote a simple timing test, and I adapted it further. The end result is that all three are very close and not even noticeable for sets < 1M. Although, technically strpos() is about twice as fast (as the docs allude to above). Here it is for your own amusement and testing purposes.
<?php
for ($i = 0; $i < 1000000; $i++ )
$o[] =
sprintf('%04d-%02d-%02d',rand(0000,9999),rand(00,99),rand(00,99));
#print_r($o);
echo "array of ".number_format($i)."\n";
###################################################################
$now = microtime(true);
for($i=0;$i<count($o);$i++) {
if(preg_match('/^[0]{4,}\-/U',$o[$i])) {
//echo "Offset #".$i." matches: ".$o[$i].PHP_EOL;
}
}
$rank['preg_match'] = (microtime(true) - $now);
###################################################################
$later = microtime(true);
for($i=0;$i<count($o);$i++) {
if(substr($o[$i],0,4) == "0000") {
//echo "Offset #".$i." matches: ".$o[$i].PHP_EOL;
}
}
$rank['substr'] = (microtime(true) - $later);
###################################################################
$after = microtime(true);
for($i=0;$i<count($o);$i++) {
if(strpos($o[$i], '0000') === 0) {
//echo "Offset #".$i." matches: ".$o[$i].PHP_EOL;
}
}
$rank['strpos'] = (microtime(true) - $after);
###################################################################
asort($rank);
print_r($rank);
?>
array of 10,000
Array
(
[strpos] => 0.00766682624817
[substr] => 0.0116670131683
[preg_match] => 0.0124950408936
)
array of 100,000
Array
(
[strpos] => 0.0817799568176
[substr] => 0.120522975922
[preg_match] => 0.125612974167
)
array of 1,000,000
Array
(
[strpos] => 0.805890083313
[substr] => 1.19799995422
[preg_match] => 1.25615906715
)
I ran out of memory with more than 1M array elements.
Achintya (2009-11-06 14:03:34)
A function I made to find the first occurrence of a particular needle not enclosed in quotes(single or double). Works for simple nesting (no backslashed nesting allowed).
<?php
function strposq($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 $i;
}
}
return false;
}
echo strposq("he'llo'character;\"'som\"e;crap", ";"); //16
?>
yasindagli at gmail dot com (2009-10-05 09:05:46)
This function finds postion of nth occurence of a letter starting from offset.
<?php
function nth_position($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 $i - 1;
}
echo nth_position('foobarbaz', 'a', 2); //7
echo nth_position('foobarbaz', 'b', 1, 4); //6
?>
digitalpbk [at] gmail.com (2009-09-30 20:37:54)
This functions throws an "Offset not contained in string" error if the offset is not in between 0 and the length of string.
KimKha (2009-09-29 01:56:07)
The following function use to redirect to URL correctly if the URL have "http://" or "https://", or to relative URL on your site.
<?php
function forward($url = NULL){
$root = "http://example.com/mydir/";
if($url == NULL) // Go to homepage
$url = $root;
else {
$pos = strpos($url, "http://");
if ($pos === false)
$pos = strpos($url, "https://");
if ($pos === false || $pos > 0) // Go to relative URL on your site
$url = $root . $url;
}
header('Location:'.$url);
}
?>
juniordez at gmail dot com (2009-09-16 09:47:16)
Function to get the string pos ($search), before the position ($pos) passed as parameter.
<?php
function strposReverse( $str, $search, $pos ){
$str = strrev($str);
$search = strrev($search);
$pos = (strlen($str) - 1) - $pos;
$posRev = strpos( $str, $search, $pos );
return (strlen($str) - 1) - $posRev - (strlen($search) - 1);
}
?>
ah dot d at hotmail dot com (2009-08-11 13:29:19)
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));
?>
bob at mailinator dot com (2009-06-03 11:26:14)
I found in a certain bit of my code that under certain circumstances, $needle could be an empty string. This caused strpos to generate an error message.
To get round it, I had to first test to see if $needle was an empty string, and then (ie 'else') go forward and do the strpos test if not.
vbracco at gmail dot com (2009-04-04 06:45:03)
This function find position of first occurrence of any $needles in a string $haystack.
Return the position as an integer. If needles is not found, strposa() will return boolean FALSE.
<?php
function strposa($haystack ,$needles=array(),$offset=0){
$chr = array();
foreach($needles as $needle){
$chr[] = strpos($haystack,$needle,$offset);
}
if(empty($chr)) return false;
return min($chr);
}
$string = "This is my string, very simple.";
echo strposa($string,array(".",","," ")); // 2
echo strposa($string,array("T")); // 0
echo strposa($string,array("Q","W")); // false
?>
lkj dot korn AT NOSPAMgmail d0t c0m (2009-04-03 12:57:27)
Note that strpos() will return false if you supply an integer (thus, this presumably applies to float, too) as needle. For example:
<?php
$id = 2; $text = '12345';
if(strpos($text, $id) === false){
echo 'Yes, is false';
}
?>
Will output 'Yes, is false', a behavior which may not be very intuitive (you'd think it would be covered by PHP's type juggling feature).
This can be easily fixed by adding $id = (string)$id; above the strpos() statement.
teddanzig at yahoo dot com (2009-03-23 09:48:06)
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 $pos;
}
else
{
return -1;
}
}
?>
peterzuzek at gmail dot com (2009-02-08 11:01:05)
A function that return the first occurance of a number in a string, if anyone needs it.
Translation/prevod:
Funkcija, ki vra?a pozicijo prve ?tevilke v besedi, ?e jo kdo potrebuje.
<?php
function firstNumPos($str) {
$poses = array(); // will be storing positions of the numbers
for($i = 0; $i < 10; ++$i) { // cycle through numbers
if(($a = strpos($str, (string)$i)) !== false) {
$poses[] = $a; // append the position of
// the first occurance of the number
}
}
if(isset($poses[0])) { // if array not empty
sort($poses); // sort to get the lowest one on the 'bottom'
return $poses[0]; // and return it
}
return false; // otherwise return false
} // firstNumPos()
?>
jburns131 at jbwebware dot com (2008-12-27 16:48:04)
The Situation:
I wanted to return TRUE if strpos returned position 0, and only position 0, without the added overhead of preg_match.
The Solution:
As PHP treats 0 (zero) as NULL, and strpos returns the int 0 (but not NULL), I used type casting and the "===" comparison operator (as it compares types) to resolve my issue.
<?php
$hayStack = "dbHost";
$needle = "db"
$needlePos = strpos($hayStack, $needle);
if((string)$needlePos === (string)0) {
echo "db is in position zero";
} else {
echo "db is NOT in position zero";
}
?>
Returns:
db is in position zero
<?php
$hayStack = "another_db_host";
$needle = "db"
$needlePos = strpos($hayStack, $needle);
if((string)$needlePos === (string)0) {
echo "db is in position zero";
} else {
echo "db is NOT in position zero";
}
?>
This returns:
db is in NOT position zero
Tim (2008-11-17 17:52:32)
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 $aStrPos;
}
else {
return false;
}
}
?>
atomkirk at hotmail dot com (2008-10-22 18:19:55)
careful that when you put a strpos in an if statement that you take note that if the string is in the 0 position it will return false, causing your control structure to think its not in the string.
samundra dot shr at gmail dot com (2008-09-27 23:40:55)
This is the code,I wrote today, I wanted to strip all the newlines, and format the output in a single line so as to lower the filesize of my php source files.
<?php
/****************************************
@ Code By : Samundra Shrestha
@ Dated : September 28,2008
P.S. Remember to remove all single line comments from the source file
otherwise the file may get corrupted.
******************************************/
if(!isset($_POST['change']) || !isset($_POST['filename']))
{
print "<b>".strtoupper("Paste the fullpath of the file")."</b>";
print "<form name='FrmChange' method='post' action='".$_SERVER['PHP_SELF']."'>";
print "<input type='textbox' name='filename' size='50px' maxlength='255'>";
print "<input type='submit' name='change' value='Start'>";
print "</form>";
}
else
{
$filename=$_POST['filename'];
if(!$fpin=@fopen($filename,"r"))
{
print "<b>Error ! File Doesn't Exists</b>";
exit();
}
$text="";
$i=0;
/*Put the contents of file into the string*/
while(!feof($fpin))
{
$text.=fread($fpin,1024);
}
$count=strlen($text);
$pos=strpos($text,"\n"); //Gives the First occurence of newline
while($i<$count)
{
if($i<$pos-1)
{
$newtext.=$text{$i}; //C Style of String Indexing
}
else
{
$pos=strpos($text,"\n",$i+1);
}
$i++;
}
$newtext.="?>"; //necessary as somehow it is removed from the original source file.
$fp=fopen("sample.txt","wb+");
fwrite($fp,$newtext);
fclose($fp);
print "File Changed Successfully.";
}
?>
The resultant code is all in one new line saved in file sample.txt
I hope, this comes handy to someone.
Cheers,
Samundra Shrestha
mickRacky (2008-09-19 11:17:45)
here's a php implementation of stdc++ string class find_first_of using strpos.
<?php
function find_first_of($haystack, $needlesAsString, $offset=0)
{
$max = strlen($needlesAsString);
$index = strlen($haystack)+1;
for($ii=0; $ii<$max;$ii++){
$result = strpos($haystack,$needlesAsString[$ii], $offset);
if( $result !== FALSE && $result < $index)
$index = $result;
}
return ( $index > strlen($haystack)? FALSE: $index);
}
?>
Example:
<?php
$test="Ralph: One of these days, Alice!!";
$look_for=":!,"; // punctuation marks
$ss = 0;
while( $answer=find_first_of($test,$look_for,$ss) ) {
echo $answer . "\n";
$ss = $answer+1;
}
?>
This prints out:
5
24
31
32
Chuzasoft Inc. ARGENTINA (2008-08-05 12:16:35)
Hi! Don't you people miss the pretty comparison operator 'LIKE' from mySql in PHP??.
I've made this funtion to emulate that method. It's for search a match string into another String
using the '%' caracter just like you do un the LIKE syntax.
For example:
<?php
$mystring = "Hi, this is good!";
$searchthis = "%thi% goo%";
$resp = milike($mystring,$searchthis);
if ($resp){
echo "milike = VERDADERO";
} else{
echo "milike = FALSO";
}
?>
Will print:
milike = VERDADERO
and so on...
this is the function:
<?php
function milike($cadena,$busca){
if($busca=="") return 1;
$vi = split("%",$busca);
$offset=0;
for($n=0;$n<count($vi);$n++){
if($vi[$n]== ""){
if($vi[0]== ""){
$tieneini = 1;
}
} else {
$newoff=strpos($cadena,$vi[$n],$offset);
if($newoff!==false){
if(!$tieneini){
if($offset!=$newoff){
return false;
}
}
if($n==count($vi)-1){
if($vi[$n] != substr($cadena,strlen($cadena)-strlen($vi[$n]), strlen($vi[$n]))){
return false;
}
} else {
$offset = $newoff + strlen($vi[$n]);
}
} else {
return false;
}
}
}
return true;
}
?>
Good luck!
paul at thiswayupdesign dot co dot uk (2008-06-18 03:48:51)
I wasn't aware of the !== operator, only the === for false. I was using this code on strpos:
<?php
while( ! ($start=@strpos($source,$startTag,$end)) === false) {
// ...
}
?>
This gave a false if the string was found at position 0, which is weird.
However using
<?php
while(($start=@strpos($source,$startTag,$end)) !== false) {
// ...
}
?>
Gives no such error and seems to work correctly
pawhox (2008-05-26 06:19:54)
Hello! I was founding a function, which finds any occurence of a string (no: first occurence). I wasn't, so I maked this function! It may be very useful.
<?php
int strnpos(string $haystack, mixed $needle, int $occurence);
?>
Example:
<?php
strnpos("I like the bananas. You like coke. We like chocolate.", "like", 2); // 24
?>
Here's code of this function:
<?php
function strnpos($base, $str, $n)
{
if ($n <= 0 || intval($n) != $n || substr_count($base, $str) < $n) return FALSE;
$str = strval($str);
$len = 0;
for ($i=0 ; $i<$n-1 ; ++$i)
{
if ( strpos($base, $str) === FALSE ) return FALSE;
$len += strlen( substr($base, 0, strpos($base, $str) + strlen($str)) );
$base = substr($base, strpos($base, $str) + strlen($str) );
}
return strpos($base, $str) + $len;
}
?>
ilaymyhat-rem0ve at yahoo dot com (2008-04-01 16:17:34)
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
?>
Suggested re-write for pink WARNING box (2008-01-11 15:45:32)
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.
Benjie (2007-10-14 04:49:22)
str_replace evaluates its arguments exactly once.
for example:
<?php
$page = str_replace("##randompicture##", getrandompicture(), $page);
?>
will call getrandompicture() once, ie it will insert the same random picture for each occurrence of ##randompicture## :(
Here is my quick and dirty workaround:
<?php
function add_random_pictures($text) {
while (($i = strpos($text, "##randompicture##")) !== false) {
$text = substr_replace($text, getrandompicture(), $i, strlen("##randompicture##"));
}
return $text;
}
$page = add_random_pictures($page);
?>
Wagner Christian (2007-08-17 01:11:54)
If you plan to use an integer as needle you need first to convert your integer into a String else it's not going to work.
For exemple :
<?php
$id = 1;
$my_text = "hel124lo";
$first_position =strpos($my_text ,substr($id,0));
?>
There are for sure some another solutions to convert an integer into a string in php.
user at nomail dot com (2007-05-15 02:21:48)
This is a bit more useful when scanning a large string for all occurances between 'tags'.
<?php
function getStrsBetween($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;
}
?>
Rich Deeson (2007-04-26 08:58:31)
Here's a somewhat more efficient way to truncate a string at the end of a word. This will end the string on the last dot or last space, whichever is closer to the cut off point. In some cases, a full stop may not be followed by a space eg when followed by a HTML tag.
<?php
$shortstring = substr($originalstring, 0, 400);
$lastdot = strrpos($shortstring, ".");
$lastspace = strrpos($shortstring, " ");
$shortstring = substr($shortstring, 0, ($lastdot > $lastspace? $lastdot : $lastspace));
?>
Obviously, if you only want to split on a space, you can simplify this:
<?php
$shortstring = substr($originalstring, 0, 400);
$shortstring = substr($shortstring, 0, strrpos($shortstring, " "));
?>
sinai [at] simnet [dot] is (2007-04-11 05:35:20)
If you want to check for either IE6 or 7 individually.
<?php
function browserIE($version)
{
if($version == 6 || $version == 7)
{
$browser = strpos($_SERVER['HTTP_USER_AGENT'], "MSIE ".$version.".0;");
if($browser == true)
{
return true;
}
else
{
return false;
}
else
{
return false;
}
?>
gal_chen123 at hotmail dot co dot il (2007-04-03 09:57:59)
this function returns the text between 2 strings:
<?php
function get_between ($text, $s1, $s2) {
$mid_url = "";
$pos_s = strpos($text,$s1);
$pos_e = strpos($text,$s2);
for ( $i=$pos_s+strlen($s1) ; ( ( $i < ($pos_e)) && $i < strlen($text) ) ; $i++ ) {
$mid_url .= $text[$i];
}
return $mid_url;
}
?>
if $s1 or $s2 are not found, $mid_url will be empty
to add an offset, simply compare $pos_s to the offset, and only let it continue if the offset is smaller then $pos_s.
jamie at jamiechong dot ca (2007-01-19 12:15:47)
Try this function to find the first position of needle before a given offset.
For example:
<?php
$s = "This is a test a is This";
$offset = strpos($s, "test");
strnpos($s, "is", $offset); // returns 17
strnpos($s, "is", -$offset); // returns 5
// Works just like strpos if $offset is positive.
// If $offset is negative, return the first position of needle
// before before $offset.
function strnpos($haystack, $needle, $offset=0)
{
if ($offset>=0)
$result=strpos($haystack, $needle, $offset);
else
{
$offset=strlen($haystack)+$offset;
$haystack=strrev($haystack);
$needle=strrev($needle);
$result=strpos($haystack, $needle, $offset);
if ($result!==false)
{
$result+=strlen($needle);
$result=strlen($haystack)-$result;
}
}
return $result;
}
?>
koteskie at gmail dot com (2006-12-18 02:31:42)
I've been looking at previous posts and came up with this function to find the start and end off an certain occurance or all occurances of needle within haystack.
I've made some minor tweaks to the code itself, like counting the length of needle only once and counting the result set array instead of using a count variable.
I also added a length parameter to the result set to use in a following substr_replace call etc...
<?php
function strpos_index($haystack = '',$needle = '',$offset = 0,$limit = 99,$return = null)
{
$length = strlen($needle);
$occurances = array();
while((($count = count($occurances)) < $limit) && (false !== ($offset = strpos($haystack,$needle,$offset))))
{
$occurances[$count]['length'] = $length;
$occurances[$count]['start'] = $offset;
$occurances[$count]['end'] = $offset = $offset + $length;
}
return $return === null ? $occurances : $occurances[$return];
}
?>
spinicrus at gmail dot com (2006-10-14 10:58:24)
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 $searchPos;
return TRUE;
}
else {
return FALSE;
}
//
}
?>
admin at xylotspace dot com (2006-09-26 19:33:28)
Yay! I came up with a very useful function. This finds a beginning marker and an ending marker (the first after the beginning marker), and returns the contents between them. You specify an initial position in order to tell it where to start looking. You can use a while() or for() loop to get all occurence of a certain string within a string (for example, taking all hyperlinks in a string of HTML code)...
<?php
function get_middle($source, $beginning, $ending, $init_pos) {
$beginning_pos = strpos($source, $beginning, $init_pos);
$middle_pos = $beginning_pos + strlen($beginning);
$ending_pos = strpos($source, $ending, $beginning_pos + 1);
$middle = substr($source, $middle_pos, $ending_pos - $middle_pos);
return $middle;
}
?>
For example, to find the URL of the very first hyperlink in an HTML string $data, use:
$first_url = get_middle($data, '<a href="', '"', 0);
It's done wonders for scraping HTML pages with certain tools on my website.
Virtual Hunter root(at)autocrash(dot)ru (2005-12-23 07:44:45)
If you want to find positions of all needle's in haystack,
you can use this one:
<?php
while (($pos=strpos($haystack,$needle,$pos+1))!==false) $pos_array[$i++]=$pos;
?>
But mind, that it will find from second char. You must use $pos=-1; before you want search from first char.
<?php
$haystack="one two three one two three one two three one two three one";
$needle="one";
$pos=-1;
while (($pos=strpos($haystack,$needle,$pos+1))!==false) $pos_array[$i++]=$pos;
?>
RESULT:
$pos_array[0] = 0
$pos_array[1] = 14
$pos_array[2] = 28
$pos_array[3] = 42
$pos_array[4] = 56
csaba at alum dot mit dot edu (2005-11-21 06:00:36)
<?php
function nthPos ($str, $needles, $n=1) {
// finds the nth occurrence of any of $needles' characters in $str
// returns -1 if not found; $n<0 => count backwards from end
// e.g. $str = "c:\\winapps\\morph\\photos\\Party\\Phoebe.jpg";
// substr($str, nthPos($str, "/\\:", -2)) => \Party\Phoebe.jpg
// substr($str, nthPos($str, "/\\:", 4)) => \photos\Party\Phoebe.jpg
$pos = -1;
$size = strlen($str);
if ($reverse=($n<0)) { $n=-$n; $str = strrev($str); }
while ($n--) {
$bestNewPos = $size;
for ($i=strlen($needles)-1;$i>=0;$i--) {
$newPos = strpos($str, $needles[$i], $pos+1);
if ($newPos===false) $needles = substr($needles,0,$i) . substr($needles,$i+1);
else $bestNewPos = min($bestNewPos,$newPos); }
if (($pos=$bestNewPos)==$size) return -1; }
return $reverse ? $size-1-$pos : $pos;
}
?>
Csaba Gabor from Vienna
dale at ucsc dot edu (2005-11-11 14:28:46)
if you want need a fast function to find the first occurrence of any ch element of an needle array this function might be of use:
<?php
$eurl = strpos_needle_array($text, array('"'=>0,'\''=>0,'>'=>0, ' '=>0, "\n"=>0), $surl);
function strpos_needle_array(& $text, $needle_ary, $offset=0){
for($ch_pos=$offset;$ch_pos<strlen($text);$ch_pos++){
if(isset($needle_ary[$text[$ch_pos]])){
return $ch_pos;
}
}
return false;
}
?>
info at quantummechanic dot com (2005-10-06 05:42:28)
this function takes a space-deliminted string as a list of potential needles and runs it against another string as a haystack.
the number of positive matches of needles within the haystack is returned as a rounded percentile.
<?php
function keyMatch($needles,$haystack) {
$nArray=split(" ",$needles);
$found=0;
$best=count($nArray);
for($i=0;$i<count($nArray);$i++) {
$pzn=strpos(strtoupper($haystack),strtoupper($nArray[$i]));
if ($pzn>-1) { $found++; }
}
$pct=($found*100)/$best;
return round($pct);
}
$test = keyMatch("the quick wolf","the quick brown fox jumps over the lazy dog");
echo($test);
?>
RESULT:
67
(because "the" and "quick" were found but "wolf" was not)
arias at elleondeoro dot com (2005-02-07 06:33:45)
If you want to get all positions in an array, you can use this function. If the optional parameter count is especified, the function will put there the number of matches.
<?php
function strallpos($pajar, $aguja, $offset=0, &$count=null) {
if ($offset > strlen($pajar)) trigger_error("strallpos(): Offset not contained in string.", E_USER_WARNING);
$match = array();
for ($count=0; (($pos = strpos($pajar, $aguja, $offset)) !== false); $count++) {
$match[] = $pos;
$offset = $pos + strlen($aguja);
}
return $match;
}
?>
admin at bwongar dot com (2005-01-20 18:17:19)
I created a useful function that returns an array with the positions within a string. For more info, read the comments:
<?php
// Returns an array in this fashion:
// array(count => position)
function strpos_array($haystack, $needle){
$kill = 0; // Kills while loop when changed
$offset = 0; // Offset for strpos()
$i = 0; // Counter, not iterator
while ($kill === 0) {
$i++;
$result = strpos($haystack, $needle, $offset);
if ($result === FALSE) { // If result is false (no more instances found), kill the while loop
$kill = 1;
} else {
$array[$i] = $result; // Set array
$offset = $result + 1; // Offset is set 1 character after previous occurence
}
}
return $array;
}
?>
takapz at flor dot it (2004-12-03 09:28:34)
here a little function for tag parsing
<?php
function parsing($tag,$string) {
$start=strpos($string,"<" . $tag . ">" );
$start=$start + strlen("<" . $tag . ">");
$end=(strpos($string, "</" . $tag . ">"));
$num= ($end - $start);
$valore=substr($string,$start,$num);
return $valore;
}
?>
philip (2004-08-25 15:52:25)
Many people look for in_string which does not exist in PHP, so, here's the most efficient form of in_string() (that works in both PHP 4/5) that I can think of:
<?php
function in_string($needle, $haystack, $insensitive = 0) {
if ($insensitive) {
return (false !== stristr($haystack, $needle)) ? true : false;
} else {
return (false !== strpos($haystack, $needle)) ? true : false;
}
}
?>
php .at. wwwcrm .dot. com (2004-08-19 10:33:04)
Watch out for type!
The following code will return "not matched", which is a little counter-intuitive.
<?php
$val1=123;
$val2="123,456,789";
if (strpos($val2, $val1)!==false) echo "matched";
else echo "not matched";
?>
When $val1 is cast to string, it behaves as you might expect:
<?php
$val1=(string)123;
$val2="123,456,789";
if (strpos($val2, $val1)!==false) echo "matched";
else echo "not matched";
?>
Hope this saves someone the couple of hours that it took me to spot it :-)
Regards,
Alex Poole
bishop (2004-04-21 15:38:36)
Code like this:
<?php
if (strpos('this is a test', 'is') !== false) {
echo "found it";
}
?>
gets repetitive, is not very self-explanatory, and most people handle it incorrectly anyway. Make your life easier:
<?php
function str_contains($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 ' . ($needlePos-1);
}
?>
amy_w at gmx dot de (2004-04-02 09:41:01)
You can use this function to find ANY occurence of a string in an array - no matter if it is just part of one of the array elements.
it returns the key of the first found occurence or false
<?php
function search_array($needle,$haystacks) {
$found=false;
foreach ($haystacks as $key => $haystack) {
if (!(strpos($haystack,$needle)===false)) {
$found=$key;
break;
}
}
return ($found);
}
?>
ebypdx at comcast dot net (2004-03-09 17:26:46)
counting the occurrences of a substring, recursive-style instead of looping.
<?php
function countSubstrs($haystack, $needle)
{
return (($p = strpos($haystack, $needle)) === false) ? 0 : (1 + countSubstrs(substr($haystack, $p+1), $needle));
}
?>
kingbusiness at hotmail dot com (2003-12-18 10:34:00)
A simple function to find the number of occurances in a string within a string
<?php
function StringCount($searchstring, $findstring)
{
return (strpos($searchstring, $findstring) === false ? 0 : count(split($findstring, $searchstring)) - 1);
}
?>
justin at visunet dot ie (2003-10-01 09:20:39)
Function:
stripos_words($haystack,'words in string')
This function finds and reports positions of all words in supplied haystack. It returns the results as an array. The array has the following structure.
Array
(
[69] => Array
(
[start] => 69
[end] => 74
[word] => honey
)
[226] => Array
(
[start] => 226
[end] => 232
[word] => cobweb
)
}
Where, for convenience, the main key also contains the positions of each found word occurrence.
If you want the main key to be 0,1,2,3,etc then set the third parameter ($pos_as_key) to false;
Hope this is of help to someone.
Cheers,
Justin :)
<?php
function stripos_words($haystack,$needles='',$pos_as_key=true)
{
$idx=0; // Used if pos_as_key is false
// Convert full text to lower case to make this case insensitive
$haystack = strtolower($haystack);
// Split keywords and lowercase them
foreach ( preg_split('/[^\w]/',strtolower($needles)) as $needle )
{
// Get all occurences of this keyword
$i=0; $pos_cur=0; $pos_found=0;
while ( $pos_found !== false && $needles !== '')
{
// Get the strpos of this keyword (if thereis one)
$pos_found = strpos(substr($haystack,$pos_cur),$needle);
if ( $pos_found !== false )
{
// Set up key for main array
$index = $pos_as_key ? $pos_found+$pos_cur : $idx++;
// Populate main array with this keywords positional data
$positions[$index]['start'] = $pos_found+$pos_cur;
$pos_cur += ($pos_found+strlen($needle));
$positions[$index]['end'] = $pos_cur;
$positions[$index]['word'] = $needle;
$i++;
}
}
}
// If we found anything then sort the array and return it
if ( isset($positions) )
{
ksort($positions);
return $positions;
}
// If nothign was found then return false
return false;
}
?>