How to locate elements in strings and arrays in PHP?

In the previous article "Take you to quickly master the replacement of PHP strings (detailed examples)" we introduced the relevant knowledge of character bed replacement in PHP in detail. Let's take a look at this article I hope this helps everyone with relevant knowledge about string positioning in PHP!

In the previous article, we learned that if you want to replace characters in a string in PHP, you need to use the substr_replace function provided by PHP With the str_replace function, this can solve the problem of PHP replacement. Similarly, string positioning is also very common in the PHP development process.

In PHP, if you want to search whether a string appears in another string, you can use the strstr function in PHP. Next, let’s take a look at how to locate and find a character. string.

<strong><span style="font-size: 20px;">strstr</span></strong>Function - Locate string element

In PHP, you can use the strstr function to search for the first occurrence of a string in another string. The basic syntax format of the strstr function is as follows:

strstr(string,search,before_search)

It should be noted that the parameter string represents the string to be searched, and the parameter search represents the string to be searched. If the parameter is not a string Then this parameter will be converted into an integer and used as the sequence number of the character. The default parameter before_search is false. If set to true, the returned result is the parameter search number. The part of the string before an occurrence.

The return result of this function is the remaining part of the string starting from the matching point. If the string to be searched is not found, the returned result is false.

Next let’s look at the use of strstr function through an example. The example is as follows:

<?php
$email  = &#39;123456789123456789@gamil.com&#39;;
echo $email. &#39;<br/>&#39;;//正常输出
$domain = strstr($email, &#39;@&#39;);//通过strstr函数来搜索@出现的第一次位置
echo $domain;
?>

Output result:

In the above example, the result returned by the strstr function is the remaining part after the string we searched for. We accomplish the purpose of locating the string through the strstr function.

When it comes to positioning matching, we have to mention regular expressions in PHP. In the above, we completed the positioning string through the strstr function. There is another function in PHP which is preg_grep() function, let’s take a look at its usage.

<strong><span style="font-size: 20px;">preg_grep</span></strong>() function-locating array elements

When it comes to search positioning in PHP, the inevitable one is regular expressions. PHP provides preg_grep() to match array elements through regular expressions. The basic syntax format of

preg_grep() function is as follows:

array preg_grep ( string $pattern , array $input [, int $flags = 0 ] )

It should be noted that the parameter pattern is defined by a regular expression , that is, the pattern to be searched, the parameter input represents the array to be searched, and the parameter flags is generally set to PREG_GREP_INVERT represents the function at this time The returned result is an array of unmatched $pattern elements.

Next let’s look at the use of the preg_grep() function through an example. The example is as follows:

<?php
$pattern = &#39;/[0-9]/&#39;;
$subject = array(&#39;weuy&#39;,&#39;r3ui&#39;,&#39;76as83&#39;,&#39;s&#39;,&#39;0ck9&#39;);
$arr = preg_grep($pattern,$subject);
show($arr);
function show($var){
    if(empty($var)){
        echo &#39;null&#39;;
    }elseif(is_array($var)||is_object($var)){
        echo &#39;
&#39;;
        print_r($var);
        echo &#39;
&#39;;
    }else{
        echo $var;
    }
}
echo &#39;<br/>&#39;;
$arr1 = preg_grep($pattern,$subject,PREG_GREP_INVERT);
show($arr1);
function show1($var1){
    if(empty1($var1)){
        echo &#39;null&#39;;
    }elseif(is_array($var1)||is_object($var1)){
        echo &#39;
&#39;;
        print_r($var1);
        echo &#39;
&#39;;
    }else{
        echo $var1;
    }
}
?>

Output result:

Through the above example, we can match the array elements, and the value of the parameter flags is different, and the results returned by the preg_grep() function are also different.

If you are interested, you can click on "PHP Video Tutorial" to learn more about PHP knowledge.

The above is the detailed content of How to locate elements in strings and arrays in PHP?. For more information, please follow other related articles on the PHP Chinese website!