To extract content from between two strings, you can use PHP's strpos() and substr() functions to implement it. First, find the position of the starting mark and calculate its end point, then find the starting position of the end mark, and finally use substr() to intercept the intermediate content. 1. Use strpos() to locate the starting mark position, and return an empty string if not found; 2. Calculate the actual starting position after the starting mark; 3. Use strpos() to search for the end mark position from the starting position, and return an empty string if not found; 4. Extract the content of the specified range through substr(). For complex scenarios such as multi-match or nested tags, consider the regular expressions preg_match() or preg_match_all(), where non-greedy patterns.? ensure that the most recent end tag is matched, and the /s modifier supports cross-row matching. Recommended DOM parsing tools when processing HTML or structured data. Be careful to avoid common errors: make sure case matching, handle missing tags, support multibyte character encoding using the mb_ function, and always add error checking logic to enhance code robustness.

To get a string between two other strings in PHP, you can use a combination of string functions like strpos() , substr() , and some basic logic. It's not built-in as a single function, but it's straightforward once you understand how to find the starting and ending positions of the part you want.

Find the content between two markers

Let's say you have a string like this:

 $text = "This is some example text with [start]important data[end] inside.";

And you want to extract whatever is between [start] and [end] . Here's how to do it:

1. Find where [start] ends — that's your starting point.
2. Find where [end] begins — that's your endpoint.
3. Use substr() to pull out the part in between.

Here's a basic function:

 function getStringBetween($text, $start, $end) {
    $startPos = strpos($text, $start);
    if ($startPos === false) return '';

    $startPos = strlen($start);
    $endPos = strpos($text, $end, $startPos);

    if ($endPos === false) return '';

    return substr($text, $startPos, $endPos - $startPos);
}

You'd call it like:

 $result = getStringBetween($text, '[start]', '[end]');
echo $result; // Outputs: important data

This works well for simple cases and avoids unnecessary complexity.

Handle multiple occurences or nested markers

If your input might contain more than one match (like multiple [start]...[end] blocks), or if there's a chance of nested markers, the above approach may not work perfectly.

In those situations, consider using regular expressions with preg_match() or preg_match_all() .

For example:

 preg_match('/$start$(.*?)$end$/s', $text, $match);
echo isset($match[1]) ? $match[1] : '';

The .*? makes it non-greedy, so it stops at the first [end] . The /s modifier allows the dot ( . ) to match newlines too, which is handy if your content spans multiple lines.

If you're dealing with HTML or structured data, parsing with DOM or XML tools would be better than regex — but for plain text, regex is often good enough.

Watch out for edge cases

There are a few things that can trip you up:

• Case sensitivity: Make sure your start/end strings exactly match in case unless you normalize both the input and search strings.
• Overlapping markers: If your end marker overlas with another occurrence, it can break the extraction.
• Missing markers: Always check if strpos() returns false before doing math on it — otherwise you'll get negative positions or errors.
• Encoding issues: If you're working with multibyte characters (eg, UTF-8), use mb_* functions instead of standard ones to avoid cutting characters in half.

So, when writing your code, always include error checks and fallbacks:

• Check if the start and end strings exist in the text.
• Avoid assuming that every [start] has a matching [end] .
• Don't hardcode values — make your function flexible enough to reuse.

Basically that's it. It's not complicated, but easy to mess up if you skip validation.

The above is the detailed content of How to get a string between two other strings in PHP. For more information, please follow other related articles on the PHP Chinese website!