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Using == vs =
Message
De
14/11/2015 06:20:13
 
 
À
14/11/2015 05:04:31
Information générale
Forum:
Visual FoxPro
Catégorie:
Autre
Titre:
Versions des environnements
Visual FoxPro:
VFP 9 SP2
OS:
Windows 10
Network:
Windows 2008 Server
Database:
MS SQL Server
Application:
Web
Divers
Thread ID:
01627149
Message ID:
01627419
Vues:
52
>>>>>>>>Is there any gotcha using == as a standard?
>>>>>>
>>>>>>I have seen issues comparing fields of unequal length, where == always fails.
>>>>>
>>>>>Why are they issues?
>>>>>Shouldn't it be failing?
>>>>>
>>>>>"John" does not equal "Johnny"
>>>>>
>>>>>The = operator has caused more bugs for me than any single feature in VFP (had one last week.)
>>>>>
>>>>>Why anyone would have a language state that "A" = "" is beyond comprehension.
>>>>
>>>>This is something that came from dBase times, and once you learn how it works, you know how and where you can use it.
>>>>
>>>>You must remember that when dBase was born, no SQL syntax or like() function existed at that time, so this kind of comparisons where an adventadge, and not a problem. Even today they are used for variuos user cases.
>>>
>>>To me, the key point is that originally, dBase was primarily for interactive use and in that setting, SET EXACT makes perfect sense.
>>>
>>>Tamar
>>
>>I'm generally OK with it.
>>
>>I mentally transform "=" into "begins with."
>>
>>My issue is with "A" = "".
>>
>>Something cannot begin with nothing. It has to begin with something.
>
>put attention on this logic
>
>"ABC"
>it begin with "A" because "ABC" == "A"+"BC"
>then definition of begin is "every left string that added ( concatenation ) with a right string return the original string"
>then
>"ABC" == "" + "ABC"
>"" == "" + ""
>and !
>"" = "" + ""
>
That's interesting logic, Fabio and it probably is what the people who wrote the language had in mind.
However when someone asks "What does 'ABC' begin with?", I will continue to answer "A", not "nothing."
Anyone who does not go overboard- deserves to.
Malcolm Forbes, Sr.
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