What's up with this?

[Joakim Christiansen]

Code: Select all

EnableExplicit

Define string$, i, checksum.a, calculatedChecksum.a

string$="10003000FCCF3091C600089528E02EBF2FEF2DBFD2"
checksum = Val("$"+Right(string$,2))
For i=0 To 19
  calculatedChecksum + Val("$"+Mid(string$,i*2+1,2))
Next
If ~calculatedChecksum+1 = checksum
  Debug "match"
Else
  Debug "no match"
EndIf
Debug checksum
Debug ~calculatedChecksum+1

Change .a to .b and it works, can someone explain why it wont work if using unsigned bytes?

[Trond]

Calculations are always done signed in PB, you have to store the value in an unsigned value to treat it as unsigned.

Code: Select all

EnableExplicit

Define string$, i, checksum.a, calculatedChecksum.a

string$="10003000FCCF3091C600089528E02EBF2FEF2DBFD2"
checksum = Val("$"+Right(string$,2))
For i=0 To 19
  calculatedChecksum + Val("$"+Mid(string$,i*2+1,2))
Next
Define checksum2.a = ~calculatedChecksum+1
If checksum2 = checksum
  Debug "match"
Else
  Debug "no match"
EndIf
Debug checksum
Debug checksum2

[Joakim Christiansen]

Aha, so the If when comparing temporary stores the value ~calculatedChecksum+1 as a signed value when it does the comparison (if I got that right).

This also fixes it:

Code: Select all

calculatedChecksum = ~calculatedChecksum+1
If calculatedChecksum = checksum

Thanks!
Now...to remember this everywhere in my code

[Zach]

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