Regular expressions on uint8 or single byte characters

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Martin Hoecker 2013-8-25

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https://ww2.mathworks.cn/matlabcentral/answers/85562-regular-expressions-on-uint8-or-single-byte-characters

I have a 200 MB text file encoded in UTF-8. My maximum array size is around 350 MB, so I can safely read it in using fread('filename','*uint8'). For using regular expressions, I need to turn this into a char array, which blows up the array size by at least a factor of two (depending on encoding, but for my application I can ignore all fancy characters), and thus leads to an "out of memory" error.

I wrote some code that breaks up the original array, so that the matching of the regular expressions works on smaller chunks, but I am still wondering: Can I somehow run regular expressions on the uint8 array? Or is there a char-like variable type that only uses 1 byte per character?

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dpb 2013-8-26

Instead of 'unit8', try 'uchar' Not sure it'll help but it is at least a character class, not an integer.

Cedric 2013-8-27

编辑：Cedric 2013-8-27

Actually, it is simpler to ask what you are trying to match instead of the pattern (copy/paste of chunk of file content or string, and an explanation of what you want to extract). With a little luck, we can perform this using STRFIND (which works on uint8 arrays) or some numeric test on uint8's.

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