How to detect whether a specified string contains another string in php

4 methods: 1. Use strpos(), the syntax is "strpos(string, another string)", and the returned position value is included. 2. Use strrpos(), the syntax is "strrpos(string, another string)", and the returned position value is included. 3. Use explode() with the syntax "explode(another string, string)". If the returned array is an empty array, it will not be included. 4. Use strstr(), the syntax is "strstr(string, another string)", if it returns FALSE, it is not included.

The operating environment of this tutorial: windows7 system, PHP version 8.1, DELL G3 computer

php detection string Whether it contains another string

Method 1: Use strpos() function to detect

strpos() function can find the string in another string The position of the first occurrence in a string (case sensitive).

If the specified character exists, return the position of the first occurrence; if not found, return FALSE.

Note: The string position starts from 0, not from 1.

Example:

<?php
header(&#39;content-type:text/html;charset=utf-8&#39;);   
$findme1 = &#39;y&#39;;
$findme2 = &#39;Y&#39;;
$mystring = &#39;xyz&#39;;
$pos1 = strpos($mystring, $findme1);
$pos2 = strpos($mystring, $findme2);
var_dump($pos1);
var_dump($pos2);
if($pos1){
	echo $mystring." 中包含指定字符 $findme1 <br>";
}else{
	echo $mystring." 中不包含指定字符 $findme1 <br>";
}
if($pos2){
	echo $mystring." 包含指定字符 $findme2 <br>";
}else{
	echo $mystring." 不包含指定字符 $findme2 <br>";
}
?>

Method 2: Use strrpos() function to detect

strrpos() function can Finds the last occurrence of a string within another string (case sensitive).

If the specified character exists, return the position of the last occurrence; if not found, return FALSE.

Example:

<?php
header(&#39;content-type:text/html;charset=utf-8&#39;);   
$findme1 = &#39;C&#39;;
$findme2 = &#39;c&#39;;
$mystring = &#39;ABC&#39;;
$pos1 = strrpos($mystring, $findme1);
$pos2 = strrpos($mystring, $findme2);
var_dump($pos1);
var_dump($pos2);
if($pos1){
	echo $mystring." 中包含指定字符 $findme1 <br>";
}else{
	echo $mystring." 中不包含指定字符 $findme1 <br>";
}
if($pos2){
	echo $mystring." 包含指定字符 $findme2 <br>";
}else{
	echo $mystring." 不包含指定字符 $findme2 <br>";
}
?>

Method 3: Use the explode() function to detect

explode() function usage Specifies the delimiter to split a string and returns an array of strings.

If the array is not an empty array (the array length is greater than 1), it is included; otherwise, the array is empty and does not contain another string

<?php
header(&#39;content-type:text/html;charset=utf-8&#39;);   
$url = "001a.gif";
$str = "a";
$con = explode($str,$url);
if (count($con)>1){
	echo $url." 中包含 ".$str;
}else{
	echo $url." 中没有包含 ".$str; 
}
?>

Method 4: Use the strstr() function to detect

The strstr() function searches for the first occurrence of a string in another string.

This function returns the rest of the string (from the matching point). Returns false if the searched string is not found.

<?php
header(&#39;content-type:text/html;charset=utf-8&#39;);   
$email = &#39;user@example.com&#39;;
$str=&#39;@&#39;;
$domain = strstr($email, $str);
if ($domain){
	echo $email." 中包含 ".$str;
}else{
	echo $email." 中没有包含 ".$str; 
}
?>

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