What is the best way to split a string into an array of Unicode characters in PHP?
In PHP < 6, what is the best way to split a string into an array of Unicode characters? If the input is not necessarily UTF-8?

I want to know whether the set of Unicode characters in an input string is a subset of another set of Unicode characters.
What is the best way to split a string into an array of Unicode characters in PHP?
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In PHP < 6, what is the best way to split a string into an array of Unicode characters? If the input is not necessarily UTF-8?

I want to know whether the set of Unicode characters in an input string is a subset of another set of Unicode characters.