strstr

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

strstrFind the first occurrence of a string

Descrição

strstr(string $haystack, string $needle, bool $before_needle = false): string|false

Returns part of haystack string starting from and including the first occurrence of needle to the end of haystack.

Nota:

This function is case-sensitive. For case-insensitive searches, use stristr().

Nota:

If it is only required to determine if a particular needle occurs within haystack, the faster and less memory intensive str_contains() function should be used instead.

Parâmetros

haystack

The input string.

needle

The string to search for.

Antes do PHP 8.0.0, se needle não for uma string, ela será convertida para um número inteiro e aplicada como o valor ordinal de um caractere. Este comportamento tornou-se defasado a partir do PHP 7.3.0 e depender dele é altamente desaconselhado. Dependendo do comportamento pretendido, o parâmetro needle deve ser explicitamente convertido em string ou uma chamada explícita para chr() deve ser realizada.

before_needle

If true, strstr() returns the part of the haystack before the first occurrence of the needle (excluding the needle).

Valor Retornado

Returns the portion of string, or false if needle is not found.

Registro de Alterações

Versão Descrição
8.0.0 O parâmetro needle agora aceita uma string vazia.
8.0.0 Passing an int as needle is no longer supported.
7.3.0 Passing an int as needle has been deprecated.

Exemplos

Exemplo #1 strstr() example

<?php
$email
= 'name@example.com';
$domain = strstr($email, '@');
echo
$domain; // prints @example.com

$user = strstr($email, '@', true);
echo
$user; // prints name
?>

Veja Também

  • stristr() - Case-insensitive strstr
  • strrchr() - Find the last occurrence of a character in a string
  • strpos() - Find the position of the first occurrence of a substring in a string
  • strpbrk() - Procura na string por um dos caracteres de um conjunto
  • preg_match() - Perform a regular expression match

add a note

User Contributed Notes 10 notes

up
44
laszlo dot heredy at gmail dot com
10 years ago
strstr() is not a way to avoid type-checking with strpos().

If $needle is the last character in $haystack, and testing $needle as a boolean by itself would evaluate to false, then testing strstr() as a boolean will evaluate to false (because, if successful, strstr() returns the first occurrence of $needle along with the rest of $haystack).

<?php
findZero
('01234'); // found a zero
findZero('43210'); // did not find a zero
findZero('0'); // did not find a zero
findZero('00'); // found a zero
findZero('000'); // found a zero
findZero('10'); // did not find a zero
findZero('100'); // found a zero

function findZero($numberString) {
if (
strstr($numberString, '0')) {
echo
'found a zero';
} else {
echo
'did not find a zero';
}
}
?>

Also, strstr() is far more memory-intensive than strpos(), especially with longer strings as your $haystack, so if you are not interested in the substring that strstr() returns, you shouldn't be using it anyway.

There is no PHP function just to check only _if_ $needle occurs in $haystack; strpos() tells you if it _doesn't_ by returning false, but, if it does occur, it tells you _where_ it occurs as an integer, which is 0 (zero) if $needle is the first part of $haystack, which is why testing if (strpos($needle, $haystack)===false) is the only way to know for sure if $needle is not part of $haystack.

My advice is to start loving type checking immediately, and to familiarize yourself with the return value of the functions you are using.

Cheers.
up
9
Gevorg Melkumyan
3 years ago
Don't confuse this function with strtr ) I lost like 1 hour on that
up
13
xslidian at lidian dot info
11 years ago
For those in need of the last occurrence of a string:

<?php
function strrstr($h, $n, $before = false) {
$rpos = strrpos($h, $n);
if(
$rpos === false) return false;
if(
$before == false) return substr($h, $rpos);
else return
substr($h, 0, $rpos);
}
?>
up
1
Julian Egelstaff
1 year ago
Lookout for logic inversion in old code!

In PHP 8, if the needle is an empty string, this function will return 0 (not false), implying the first character of the string matches the needle. Before PHP 8, it would return false when the needle is an empty string.

There other string functions that are affected by similar issues in PHP 8: strpos(), strrpos(), stripos(), strripos(), strchr(), strrchr(), stristr(), and this function, strstr()

If you are checking if the return value === false then you will be misled by this new behaviour. You also need to check if the needle was an empty string. Basically, something like this:

<?php
$result
= $needle ? strstr($haystack, $needle) : false;
?>
up
17
gruessle at gmail dot com
13 years ago
Been using this for years:

<?php
/**
*
* @author : Dennis T Kaplan
*
* @version : 1.0
* Date : June 17, 2007
* Function : reverse strstr()
* Purpose : Returns part of haystack string from start to the first occurrence of needle
* $haystack = 'this/that/whatever';
* $result = rstrstr($haystack, '/')
* $result == this
*
* @access public
* @param string $haystack, string $needle
* @return string
**/

function rstrstr($haystack,$needle)
{
return
substr($haystack, 0,strpos($haystack, $needle));
}
?>

You could change it to:
rstrstr ( string $haystack , mixed $needle [, int $start] )
<?php

function rstrstr($haystack,$needle, $start=0)
{
return
substr($haystack, $start,strpos($haystack, $needle));
}

?>
up
9
w3b_monk3y at yahoo dot com
15 years ago
If you want to emulate strstr's new before_needle parameter pre 5.3 strtok is faster than using strpos to find the needle and cutting with substr. The amount of difference varies with string size but strtok is always faster.
up
9
brett dot jr dot alton at gmail dot com
16 years ago
For the needle_before (first occurance) parameter when using PHP 5.x or less, try:

<?php
$haystack
= 'php-homepage-20071125.png';
$needle = '-';
$result = substr($haystack, 0, strpos($haystack, $needle)); // $result = php
?>
up
-2
trent dot renshaw at objectst dot com dot au
9 years ago
> root at mantoru dot de

PHP makes this easy for you. When working with domain portion of email addresses, simply pass the return of strstr() to substr() and start at 1:

substr(strstr($haystack, '@'), 1);
up
-20
root at mantoru dot de
16 years ago
Please note that $needle is included in the return string, as shown in the example above. This ist not always desired behavior, _especially_ in the mentioned example. Use this if you want everything AFTER $needle.

<?php
function strstr_after($haystack, $needle, $case_insensitive = false) {
$strpos = ($case_insensitive) ? 'stripos' : 'strpos';
$pos = $strpos($haystack, $needle);
if (
is_int($pos)) {
return
substr($haystack, $pos + strlen($needle));
}
// Most likely false or null
return $pos;
}

// Example
$email = 'name@example.com';
$domain = strstr_after($email, '@');
echo
$domain; // prints example.com
?>
up
-25
leo dot nard at free dot fr
19 years ago
When encoding ASCII strings to HTML size-limited strings, sometimes some HTML special chars were cut.

For example, when encoding "��" to a string of size 10, you would get: "à&a" => the second character is cut.

This function will remove any unterminated HTML special characters from the string...

<?php
function cut_html($string)
{
$a=$string;

while (
$a = strstr($a, '&'))
{
echo
"'".$a."'\n";
$b=strstr($a, ';');
if (!
$b)
{
echo
"couper...\n";
$nb=strlen($a);
return
substr($string, 0, strlen($string)-$nb);
}
$a=substr($a,1,strlen($a)-1);
}
return
$string;
}
?>
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