PHP strpos Function: How it Works with Examples

Sometimes the string you expect is there, but strpos function gives a surprise in PHP. It may show the result in a new line or a position that does not match what you had in mind.

What the strpos Function Is in PHP

strpos means “string position.” It looks for one string inside another and gives the location where it starts.

Here is the syntax:

strpos($haystack, $needle, $offset)

You provide the main text, what you want to find, and optionally where to start looking.

• It returns the index (position) where the match begins.
• If it does not find a match, it gives false.
• To avoid confusion, check it with === so 0 does not look like false.

Here is an example:

echo strpos("apple pie", "pie"); // 6

“pie” starts at position 6 inside “apple pie”.

echo strpos("banana", "a"); // 1  

The first “a” appears at position 1. It only shows the first match.

Case-sensitive behavior:

echo strpos("Hello", "h"); // false  
echo strpos("Hello", "H"); // 0

PHP treats uppercase and lowercase as different. “h” and “H” do not match.

Find the first occurrence:

echo strpos("abc abc abc", "abc"); // 0

It finds “abc” three times but only returns the position of the first one.

Handle Case-Insensitive

strpos sees “Test” and “test” as different. Use stripos when you want to ignore the case.

It acts just like strpos, but does not care about capital letters. For example:

echo stripos("Make it Simple", "simple"); // 8

“Simple” starts with a capital letter, but stripos still finds “simple” inside it.

• Use stripos when user input may use upper or lower case.
• This avoids missed matches from small changes.
• It makes your code more flexible and less strict.

When you check text, decide whether case matters. If it does not, use stripos. That keeps your logic clear and avoids false results. It leads to bugs that take time to trace if you skip this.

Combine strpos with Other String Functions

You can mix strpos with substr to cut out parts of text after a match.

$text = "user:john";
$pos = strpos($text, ":");
$name = substr($text, $pos + 1); // "john"

This grabs the part of the string after the colon. It helps break values apart.

You can also clean and trim the result:

$data = "  note=important ";
$start = strpos($data, "=");
$value = trim(substr($data, $start + 1)); // "important"

trim() clears spaces, substr() grabs the value after the =, and strpos() finds the position.

Examples

Find the domain from the email:

$email = "[email protected]";
echo substr($email, strpos($email, "@") + 1); // example.com

This cuts everything after the @ symbol. It shows the domain of the email.

Get part before a colon:

$line = "lang:PHP";
echo substr($line, 0, strpos($line, ":")); // lang

This slices the text before the colon. It gives the key from a key:value pair.

Check if the sentence starts with a word:

$sentence = "Welcome to the show";
echo strpos($sentence, "Welcome") === 0 ? "Yes" : "No"; // Yes

It checks if “Welcome” starts at position 0. That tells you if the string begins with that word.

Wrapping Up

In this article, you learned how to use strpos to find parts of strings. You also saw how to work with stripos, substr, and trim.

Here is a quick recap:

• Use strpos to find where one string appears in another.
• It gives 0 or higher if it finds it, false if it does not.
• Use stripos when you want to skip case checks.
• Combine with substr to cut or extract text.

FAQs