The basic logic of fuzzy search using stripos

When developing web applications, we often need to search in a large amount of data. For ordinary exact matches, strpos or other string functions may be used. However, when we need to do fuzzy searches, PHP provides a very practical function - stripos . This function allows us to find the location of a substring in a string, and is case-insensitive when searching.

1. Basic principles of stripos function

The stripos function is used to find where a string (substring) first appears in another string. Unlike strpos function, strpos ignores case when searching. This means that no matter whether the target string is uppercase or lowercase, stripos can correctly find the match.

Function Syntax

 stripos(string $haystack, string $needle, int $offset = 0): int|false

• haystack : The target string to search for.

• needle : The substring to be found.

• offset (optional): Start the search from where in the target string, the default is 0 (start from scratch).

If a match is found, stripos returns the start position (index position) of the matching substring, and if not found, false .

2. Fuzzy search application example

Suppose we have a database that stores email addresses for multiple users. We hope that when a user enters a search keyword, all email addresses related to the keyword can be found through fuzzy matching.

Here is a simple PHP example that demonstrates how to implement fuzzy search using stripos :

 <?php
// Search keywords entered by users
$searchKeyword = "example";

// Suppose there is an array of email addresses
$emailList = [
    "user1@m66.net",
    "user2@m66.net",
    "contact@m66.net",
    "admin@example.com",
    "test@example.com"
];

// Store matching results
$matchingEmails = [];

// Iterate through the email address array，Perform a fuzzy search
foreach ($emailList as $email) {
    if (stripos($email, $searchKeyword) !== false) {
        $matchingEmails[] = $email;
    }
}

// Output matching results
echo "Matched email address：\n";
foreach ($matchingEmails as $email) {
    echo $email . "\n";
}
?>

Code parsing:

1. We define a search keyword $searchKeyword and assume we have an array of email addresses $emailList .

2. Use foreach to iterate through each email address and call stripos for fuzzy matching. If a match is found, the email address is added to the $matchingEmails array.

3. Finally, we print out all matching email addresses.

In the above example, stripos ignores case and can effectively find email addresses containing keywords.

3. Application scenarios

Stripos function is suitable for many fuzzy search scenarios, common applications include:

• Search engines : Find documents, content or records containing the keywords entered by users.

• Log Analysis : Find specific keywords or error messages in a large number of log files.

• Content filtering : Filter out unnecessary content or perform content review based on specific keywords.

4. Things to note

1. Performance issues : Although the scripos function is very convenient, if the data volume is very large, frequent call to the function may affect performance. Consider using the database's full-text retrieval function or caching technology to improve efficiency.

2. Matching method : stripos is case-insensitive, but if you need to be case-sensitive, you can use the strpos function.

3. Match position : stripos returns the starting position of the match. If you need to obtain more detailed matching information, you can use it in combination with other functions.