PHP：如何从（多字节）字符串中提取所有预定义的子字符串？

Question

I'd like to split a string (representing a word) into letters and predefined multi-letter sequences. In other words I'd like to extract predefined substrings form a string matching in a "greedy" way and in order in which they occur.

For example if I my array of substrings contained all latin letters plus Polish digraphs: ['ch', 'cz', 'dz', 'dź', 'dż', 'rz', 'sz'] then szczebrzeszyn would be parsed into ['sz', 'cz', 'e', 'b', 'rz', 'e', 'sz', 'y', 'n'] .

Of course I could write some nested loops comparing character by character, but maybe there is some creative and more efficient way to obtain such result using the built-in string functions? How can I do this in PHP in an efficient and multi-byte safe way?

Answer 1

preg_match_all('/sz|cz|\X/u', 'wszczęcie', $matches);
print_r($matches);

returns:

Array
(
    [0] => Array
        (
            [0] => w
            [1] => sz
            [2] => cz
            [3] => ę
            [4] => c
            [5] => i
            [6] => e
        )
)

So the above code seems to do the job. The important points are: the substrings are matched in the order they are provided, so longer ones should go first ( 'cz' should be matched before 'c' , etc.). And the u flag is important to make it multi-byte safe.