要從兩個字符串之間提取內容，可以使用PHP的strpos()和substr()函數組合實現。首先找到起始標記的位置併計算其結束點，接著查找結束標記的起始位置，最後用substr()截取中間內容。 1. 使用strpos()定位起始標記位置，若未找到則返回空字符串；2. 計算起始標記後的實際開始位置；3. 使用strpos()從起始位置搜索結束標記位置，若未找到則返回空字符串；4. 通過substr()提取指定範圍的內容。對於復雜場景如多匹配或嵌套標記，可考慮正則表達式preg_match()或preg_match_all()，其中非貪婪模式.?可確保匹配最近的結束標記，/s修飾符支持跨行匹配。處理HTML或結構化數據時推薦DOM解析工具。注意避免常見錯誤：確保大小寫匹配、處理缺失標記情況、使用mb_函數支持多字節(jié)字符編碼，並始終添加錯誤檢查邏輯以增強代碼魯棒性。

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 occurrences 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 overlaps 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.

基本上就這些。 It's not complicated, but easy to mess up if you skip validation.

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