PHP中strlen函数统计字符异常求助：预期输出11实际得23

Hey there! Let's figure out why your strlen() call is returning 23 instead of the expected 11 for the string "Subdivision".

The Root Cause #

First, a quick reminder: PHP's strlen() counts bytes, not characters. For standard ASCII English text like "Subdivision", each character takes up 1 byte—so a length of 11 makes perfect sense. A result of 23 means your string is hiding extra, invisible bytes. These are usually things like zero-width spaces, non-printable control characters, or leftover formatting gunk from copying/pasting from rich text sources (like Word docs or formatted web pages).

Steps to Diagnose the Hidden Bytes #

Let's expose those sneaky extra bytes using bin2hex() to see the raw hex representation of your string:

$string = "Subdivision";
echo bin2hex($string);

For a clean "Subdivision", you should see this output:
5375626469766973696f6e
If your output is twice as long (or longer), that confirms extra bytes are mixed in—for example, zero-width spaces show up as e2808b in UTF-8.

Fix the Issue #

To strip out all non-alphabetic characters (including the hidden ones), use a regular expression to clean your string:

$string = "Subdivision";
// Keep only uppercase and lowercase English letters
$cleanedString = preg_replace('/[^a-zA-Z]/', '', $string);
echo strlen($cleanedString); // This should now output 11

If you need to preserve other valid characters (like spaces or punctuation), adjust the regex to include them—for example, /[^a-zA-Z\s]/ would keep spaces alongside letters.

Bonus Tip for UTF-8 Text #

While this isn't the issue here, if you regularly work with multi-byte languages or UTF-8 text, swap strlen() for mb_strlen() to count actual characters (not bytes):

echo mb_strlen($string, 'UTF-8');

内容的提问来源于stack exchange，提问作者sushil vishwakarma