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Resolved Comparing 2 strings

  1. Misc
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  1. Dean Helsley
    Dean Helsley
  2. PowerBuilder
  3. Tuesday, 17 August 2021 17:59 PM UTC

I'm confused by the results of a string comparison.  I only discovered this because it's causing an issue with some legacy code we are migrating for a client from the mainframe.

I thought any non-blank value would be greater than a space, but the minus sign is not.  In the debugger, I added the following watch expressions:

 "a" > " "  (this is true)

 "-" > " "  (this is false)

Is this a bug or expected behavior?  It's causing an issue when running the client's converted code because a loop is exiting when it shouldn't based on that comparison.  I don't know why someone would have a single dash as a key value, but that's what's in the data.  That might be an EBCDIC to ASCII conversion issue which we're also investigating.  Regardless, I would expect a char(45) to be greater than a char(32).

 

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Responses (3)
John Fauss
John Fauss Accepted Answer Pending Moderation
  1. Tuesday, 17 August 2021 19:13 PM UTC
  2. PowerBuilder
  3. # 1

This is not a definitive answer, Dean, but if one of the values being compared is ASCII-encoded ANSI, then this behavior could be due to comparison of Unicode with ANSI. Since v10, PB strings by default are represented using Unicode16LE (16-bit, Little Endian) encoding. If the information being processed is from a file that contains ANSI (ASCII127) and the information is not translated to Unicode, there could very well be comparison issues.

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Miguel Leeuwe
Miguel Leeuwe Accepted Answer Pending Moderation
  1. Wednesday, 18 August 2021 03:56 AM UTC
  2. PowerBuilder
  3. # 2

In addition to what John has said, if you convert the char values it will work (cannot be strings):

 

integer li_1, li_2
li_1 = asc('-')
li_2 = asc(' ')
if li_1 > li_2 then
....
end if
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Dean Helsley
Dean Helsley Accepted Answer Pending Moderation
  1. Wednesday, 18 August 2021 15:08 PM UTC
  2. PowerBuilder
  3. # 3

I understand about the encoding, and that did cross my mind, however in a simple PB debugger watch expression, apparently '-' is not greater than a space.  That just seems wrong to me.

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Miguel Leeuwe
  1. Miguel Leeuwe
  2. Wednesday, 18 August 2021 16:09 PM UTC
Yes I agree. I guess it has something to do on what's preferred when sorting data on a string column / value. (first all the 'funny' characters, then the rest).
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