unicode letter or character frequency in php or vb.net

AM doing a letter frequency analyzer program just like this website 开发者_开发问答http://www.characterfrequencyanalyzer.com/, but i don't know the right algorithm. Of course simple looping should work if it where just english letters, but the trick is it should work with unicode letters like arabic ,chinese etc.

how do i do this? if i can get sample code in vb.net or php, or an algol, i would be thankful.

thanks

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well ... maybe you should ask yourself more prcisely what it really is that you want to measure, as chinese got no 'letters' for example.

why not just using an associative array (character code -> counter)?