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Common string manipulation functions in PHP, str_split and mb_str_split, are both used to split a string into an array of specified lengths, but they work very differently. When dealing with multibyte character sets, such as UTF-8 encoding, str_split has limitations, and in such cases, using mb_str_split is more appropriate. This article will explore the differences between these two functions and when you should opt for mb_str_split instead of str_split.
Let's first quickly review the basic functions and usages of str_split and mb_str_split.
str_split: This function splits a string into an array of specified lengths. It is a built-in PHP function that works with ASCII character sets but cannot properly handle multibyte characters.
Example:
$str = "Hello World";
$result = str_split($str, 2); // Returns: ['He', 'll', 'o ', 'Wo', 'rl', 'd']
mb_str_split: This function, from the multibyte string extension (mbstring), splits a string by characters and can properly handle UTF-8 or other multibyte character encodings.
Example:
$str = "你好，世界";
$result = mb_str_split($str, 1); // Returns: ['你', '好', '，', '世', '界']
str_split has a major issue in that it does not support multibyte character sets. For instance, in UTF-8 encoding, a Chinese character takes up multiple bytes, but str_split splits the string by bytes, not by characters. This means it cannot handle strings with multibyte characters (such as Chinese or Japanese characters) correctly.
Consider the following example:
$str = "你好";
$result = str_split($str, 1);
print_r($result);
The output might be:
Array
(
[0] => "你"
[1] => "好"
)
Although it looks fine, in reality, str_split splits the string by bytes rather than characters. If the string contains multibyte characters, str_split can lead to unnecessary corruption or incorrect results.
mb_str_split is designed specifically for multibyte character sets. It can correctly identify and split multibyte characters, whether they are in UTF-8, GBK, or other encodings. By using mb_str_split, we can ensure that the string is split by characters, not by bytes.
Let's continue with the example above:
$str = "你好";
$result = mb_str_split($str, 1);
print_r($result);
The output will be:
Array
(
[0] => "你"
[1] => "好"
)
At this point, mb_str_split correctly splits the string into an array with one character per element, avoiding any byte-level splitting issues.
If your project involves multibyte character sets (such as UTF-8 encoded Chinese, Japanese, Korean, etc.), you should use mb_str_split when splitting strings. This is especially true when dealing with user input, storing data, or working with multilingual content, as using str_split in these cases may lead to unnecessary issues.
Here are some scenarios where you should consider using mb_str_split:
Handling multilingual content: Such as Chinese, Japanese, Korean, and other multibyte character sets.
User input: User-provided text may contain multibyte characters, so using mb_str_split is a safer choice.
Character encoding conversion: When you need to convert character encodings and split strings by characters, mb_str_split offers better compatibility.
Although mb_str_split provides better compatibility when dealing with multibyte characters, its performance is slightly lower than str_split because it needs to handle character encoding and multibyte characters. For large-scale string processing, especially when dealing with vast amounts of text data, performance testing and optimization may be necessary.
For simple ASCII strings, str_split may be more efficient, but if there are multibyte characters involved, using mb_str_split is the more reliable choice.
str_split: Suitable for ASCII strings, but cannot handle multibyte characters correctly.
mb_str_split: Suitable for multibyte character sets (such as UTF-8 encoding), and can correctly handle strings containing multibyte characters.
When you need to work with multibyte character sets, you should prioritize using mb_str_split to avoid errors or inconsistencies caused by encoding issues. If you're certain that your string only contains single-byte characters, str_split is a lighter option.
We hope this article helps you understand how to choose the correct splitting function for multibyte string handling.
