How to determine whether a specified character is in a string in php

Judgment method: 1. Use strpos(). If the specified character exists, return the position where it first appears; if not found, return FALSE. 2. Use strrpos(). If the specified character exists, it returns the position of the last occurrence; if it is not found, it returns FALSE. 3. Use stripos(), if it is, return the position where it first appears. 4. Use strripos(), if it is, return the last occurrence position. 5. Use explode(), if the returned array is not empty.

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

php Detect whether a string contains another string

Method 1: Use the strpos() function to detect

The strpos() function can find characters The position of the first occurrence of a string within another 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 stripos() function

stripos() function to find The position of the first occurrence of a string within another string (case-insensitive).

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

<?php
header(&#39;content-type:text/html;charset=utf-8&#39;);   
$findme1 = &#39;y&#39;;
$findme2 = &#39;Y&#39;;
$mystring = &#39;xyz&#39;;
$pos1 = stripos($mystring, $findme1);
$pos2 = stripos($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 4: Use the strripos() function to detect

The strripos() function can find a string in another string The position of the last occurrence in (not case sensitive).

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

<?php
header(&#39;content-type:text/html;charset=utf-8&#39;);   
$findme1 = &#39;C&#39;;
$findme2 = &#39;c&#39;;
$mystring = &#39;ABC&#39;;
$pos1 = strripos($mystring, $findme1);
$pos2 = strripos($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 5: Use the explode() function to detect

explode() function uses the specified 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; 
}
?>

Recommended learning: "PHP Video Tutorial"

The above is the detailed content of How to determine whether a specified character is in a string in php. For more information, please follow other related articles on the PHP Chinese website!