Convert UNICODE to ASCII

[Roberto]

Can someone explain this to me?

I was looking for a way to convert UNICODE to ASCII and found a similar code here in the Cache group:

CONVERTUNICODE(str)
NEW j,strlength
Set returnValue=""
Set strlength=$LENGTH(str)
For j=1:1:strlength {
Set char=$EXTRACT(str,j)
Set char=$A(char)
Set returnValue=returnValue _ $C($ZBOOLEAN(char,64,6))
}

Set returnValue=$EXTRACT(returnValue,2)
Quit returnValue

Can someone explain why this would work?

I've tested with some UNICODE characters and it does work.

-Roberto

[David Whitten]

If I remember correctly, UNICODE is a strict superset of ASCII.

An ASCII character is directly stored as the same bit pattern

as the bottom 7 bits of the UNICODE two byte sequence.

The top 9 bits are all zero for the ASCII in UNICODE bit sequence.

It appears that the UNICODE Cache $EXTRACT, gives back the UNICODE representation of the character, and since it is a number from 0 to 127, when $CHARACTER is given it as an input, it gives back the single byte ASCII character.

Perhaps someone else on the mailing list could explain the significance of $ZBOOLEAN(char,64,6) ... I know 64 is 2 ** 6, but I think ASCII has

7 significant bits (0 thru 127), so I think I am missing something in

that part of the code.

Dave

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[Roberto]

I can't seem to find the original post from this group where I found this code, but I remember that Bill from Intersystems says that the code works.

I did test and it does work.

I'm just concerned why are we discarding the first character though.

-Roberto

[Roberto]

Here's the original post where I copied the code from:

https://groups.google.com/forum/#!searchin/intersystems-public-cache/unicode$20to$20ascii%7Csort:relevance/intersystems-public-cache/YxJbyCJHiGE/hBxGHe7wdN4J

-Roberto