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SUBSTR indexes in free42
07-31-2021, 01:01 PM
Post: #1
SUBSTR indexes in free42
Hello, playing with the new string functions in free42 I notice that it seems SUBSTR uses an Y index starting from 0, while the X index starts from 1.
So to get the Nth character of a string or element of a list, you have N-1 in Y and N in X
Is it the expected behaviour?

Or maybe the intepretation is different: SUBSTR takes element from Y included to X excluded?

As a simple exercise, this is a reusable routine to get the nth string character or list element:

LBL "NTH"
FUNC 21
RCL ST X
1
-
X<>Y
SUBSTR
RTN

thank you
Mark
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07-31-2021, 03:50 PM
Post: #2
RE: SUBSTR indexes in free42
(07-31-2021 01:01 PM)mtern Wrote:  Or maybe the intepretation is different: SUBSTR takes element from Y included to X excluded?

Yes. String index is 0-based, end excluded → string length = end - begin
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08-01-2021, 03:48 PM
Post: #3
RE: SUBSTR indexes in free42
(07-31-2021 03:50 PM)Albert Chan Wrote:  
(07-31-2021 01:01 PM)mtern Wrote:  Or maybe the intepretation is different: SUBSTR takes element from Y included to X excluded?

Yes. String index is 0-based, end excluded → string length = end - begin

Thank you for the clarification.
Mark
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