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Topic: Associative Arrays (Read 440 times) |
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g3nrw
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Associative Arrays
« Thread started on: Nov 16th, 2013, 10:16am » |
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I want to set up a string array CAT$(9999), with each element containing a two-character code followed by a free-text description. For example:
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CAT$(14)="EX 035 CW Clipping 4mS"
CAT$(15)="EX 035 CW Clipping 6mS"
CAT$(35)="MD Mode USB"
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Is there a quick BB4W way to find the free text for an element once the two-character code is known, without doing a (perhaps lengthy) search for a match from the start of the array?
I thought of setting up the entries in strict alphabetical order of 2-character code, then doing a binary chop, but is there a quicker way?
Ian
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admin
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Re: Associative Arrays
« Reply #1 on: Nov 16th, 2013, 1:09pm » |
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on Nov 16th, 2013, 10:16am, g3nrw wrote:| I thought of setting up the entries in strict alphabetical order of 2-character code, then doing a binary chop, but is there a quicker way? |
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There's unlikely to be a quicker way, since SORTLIB is very fast (it's a machine-code shell sort) and the binary chop is very efficient. So if speed is your main concern that's the way I would recommend. Do remember to use the latest version of SORTLIB and specify ASCII sorting, so you can use regular comparison operators in the binary chop:
http://bb4w.wikispaces.com/Searching+ordered+lists
As far as alternative methods are concerned, you could prefix each element with a unique character and use INSTR:
Code: DIM CAT$(9999)
CAT$() = "*"
CAT$(14) = "*EX 035 CW Clipping 4mS"
CAT$(15) = "*EX 035 CW Clipping 6mS"
CAT$(35) = "*MD Mode USB"
all$ = SUM(CAT$())
REPEAT
INPUT "Enter two-letter code: "code$
I% = INSTR(all$, "*"+code$)
IF I% THEN
J% = INSTR(all$, "*", I%+1)
PRINT "Free text is " MID$(all$, I%+4, J%-I%-4)
ELSE
PRINT "Not found"
ENDIF
UNTIL FALSE
Of course you'd need to use BB4W version 6 if the total length of all the array elements exceeds 65535 characters.
Richard.
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g3nrw
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Posts: 74
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Re: Associative Arrays
« Reply #2 on: Nov 18th, 2013, 7:14pm » |
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on Nov 16th, 2013, 1:09pm, Richard Russell wrote:There's unlikely to be a quicker way,
[snip]
Richard. |
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Thanks Richard. Food for thought
Ian
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