Whether the php string contains a certain string

When writing a program, you often need to process strings. The most basic thing is to search for strings. To detect whether a string contains a specified string in PHP, you can use the following function

strpos(string,find[,start]);

string: required. Specifies the string to search for.

find: required. Specifies the characters to search for.

start: Optional. Specifies the location from which to start the search.

Example (Recommended learning: PHP programming from entry to proficiency)

<?php
$str = &#39;abcdefghi&#39;;
$find   = &#39;ab&#39;;
$pos = strpos($str, $find);

// 注意：这里使用的是 === 不能使用 ==
// 原因：第一个字符串的位置是从0开始。如果这个字符串位于字符串的开始的地方，就会返回0。
// 如果没有字符串 就返回false。
// 为了区分0和false就必须使用等同操作符 === 或者 ！==

//1、使用 === 操作符
if ($pos === false) {
    echo "$find不在$str中";
} else {
    echo "$find在$str中";
}

//或2、使用 ！== 操作符
if($pos !== false){
	echo "$find在$str中";
}else{
	echo "$find不在$str中"; 
}
?>

explode

Use explode to judge. The PHP judgment string contains the following code:

function checkstr($str){
 $needle ='a';//判断是否包含a这个字符
 $tmparray = explode($needle,$str);
 if(count($tmparray)>1){
 return true;
 } else{
 return false;
 }
}

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