How to determine whether a string contains dots in php

3 methods: 1. Use stripos(), the syntax is "stripos($str, ".")", and the returned position value is included. 2. Use strripos(), the syntax is "strripos($str, ".")", and the returned position value is included. 3. Use explode() with the syntax "explode($str,".")". If the returned array is an empty array, it will not be included. Otherwise, it will be included.

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

php detection string Methods to determine whether a string contains specified characters

Method 1: Use the stripos() function to detect

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

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;);   
$str = &#39;12.36&#39;;
$pos = stripos($str, ".");

var_dump($pos);
if($pos){
	echo $str." 中指定字符 圆点.<br>";
}else{
	echo $str." 中不包含指定字符 圆点.<br>";
}
?>

Method 2: Use strripos() function to detect

strripos() function can Finds the last occurrence of a string within another string (case-insensitive).

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;);   
$str = &#39;12.36.3&#39;;
$pos = strripos($str, ".");

var_dump($pos);
if($pos){
	echo $str." 中指定字符 圆点.<br>";
}else{
	echo $str." 中不包含指定字符 圆点.<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 = ".";
$con = explode($str,$url);
if (count($con)>1){
	echo $url." 中包含 圆点".$str;
}else{
	echo $url." 中没有包含圆点 ".$str; 
}
?>

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