reversing the comparison
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From: Cor on 22 Jul 2010 04:53 Tom, Why C# and Java You can do it in VB too If (((Not X) = 1)) = False) then However, it keeps showing for me the knowledge of the developer who did this. Cor "Tom Shelton" <tom_shelton(a)comcast.invalid> wrote in message news:i28dvd$35b$1(a)news.eternal-september.org... > on 7/21/2010, ralph supposed : >> On Wed, 21 Jul 2010 19:07:31 -0600, Tom Shelton >> <tom_shelton(a)comcast.invalid> wrote: >> >> >>> >>> The only reason boolean returns came into it is because most modern >>> languages force conditionals (if, while, etc) to only accept a statement >>> that evaluates to a boolean - so the old constant == varialbe convention >>> isn't a requirement.... You get a compiler error in either direction. >>> >> >> But the question had nothing to do with *other languages* it was a >> C/C++ example, and placing a Constant first has always been a nice >> habit to get into when doing comparisons, period. >> > > To prevent an ACCIDENTAL assignment. I understand that. And that is the > basic answer... > >> In the example the other operand was a function, so an error was >> likely in either case, but likely had nothing to do with the >> programmer employing the convention. >> >> And where did you get the idea you CAN NOT do an assignment in a >> conditional statement???? >> > > I didn't say you can't... I didn't even say you would want to. It is > just a common old C/C++ bug to ACCIDENTLY do an assignment. The > convention of constant first was simply to avoid that mistake. > > You can even do an assignent in C# and Java - it's jsut the result of your > expresion must be a boolean. > > string line; > while ((line = reader.ReadLine()) != null) > { > } > > > > -- > Tom Shelton > > >
From: Henning on 22 Jul 2010 06:08 And where is the assignement? /Henning "Cor" <Notmyfirstname(a)planet.nl> skrev i meddelandet news:e9p1jtXKLHA.4240(a)TK2MSFTNGP06.phx.gbl... > Tom, > > Why C# and Java > > You can do it in VB too > > If (((Not X) = 1)) = False) then > > However, it keeps showing for me the knowledge of the developer who did > this. > > Cor > > "Tom Shelton" <tom_shelton(a)comcast.invalid> wrote in message > news:i28dvd$35b$1(a)news.eternal-september.org... >> on 7/21/2010, ralph supposed : >>> On Wed, 21 Jul 2010 19:07:31 -0600, Tom Shelton >>> <tom_shelton(a)comcast.invalid> wrote: >>> >>> >>>> >>>> The only reason boolean returns came into it is because most modern >>>> languages force conditionals (if, while, etc) to only accept a >>>> statement that evaluates to a boolean - so the old constant == varialbe >>>> convention isn't a requirement.... You get a compiler error in either >>>> direction. >>>> >>> >>> But the question had nothing to do with *other languages* it was a >>> C/C++ example, and placing a Constant first has always been a nice >>> habit to get into when doing comparisons, period. >>> >> >> To prevent an ACCIDENTAL assignment. I understand that. And that is the >> basic answer... >> >>> In the example the other operand was a function, so an error was >>> likely in either case, but likely had nothing to do with the >>> programmer employing the convention. >>> >>> And where did you get the idea you CAN NOT do an assignment in a >>> conditional statement???? >>> >> >> I didn't say you can't... I didn't even say you would want to. It is >> just a common old C/C++ bug to ACCIDENTLY do an assignment. The >> convention of constant first was simply to avoid that mistake. >> >> You can even do an assignent in C# and Java - it's jsut the result of >> your expresion must be a boolean. >> >> string line; >> while ((line = reader.ReadLine()) != null) >> { >> } >> >> >> >> -- >> Tom Shelton >> >> >>
From: Cor on 22 Jul 2010 06:23 Ever thought at the idea that X is a function likewise the C and C# sample from Tom. With option strict on you need to convert first to Boolean, but I did not find that real relevant for this newsgroup. "Henning" <computer_hero(a)coldmail.com> wrote in message news:i295a9$l2v$1(a)news.eternal-september.org... > And where is the assignement? > > /Henning > > "Cor" <Notmyfirstname(a)planet.nl> skrev i meddelandet > news:e9p1jtXKLHA.4240(a)TK2MSFTNGP06.phx.gbl... >> Tom, >> >> Why C# and Java >> >> You can do it in VB too >> >> If (((Not X) = 1)) = False) then >> >> However, it keeps showing for me the knowledge of the developer who did >> this. >> >> Cor >> >> "Tom Shelton" <tom_shelton(a)comcast.invalid> wrote in message >> news:i28dvd$35b$1(a)news.eternal-september.org... >>> on 7/21/2010, ralph supposed : >>>> On Wed, 21 Jul 2010 19:07:31 -0600, Tom Shelton >>>> <tom_shelton(a)comcast.invalid> wrote: >>>> >>>> >>>>> >>>>> The only reason boolean returns came into it is because most modern >>>>> languages force conditionals (if, while, etc) to only accept a >>>>> statement that evaluates to a boolean - so the old constant == >>>>> varialbe convention isn't a requirement.... You get a compiler error >>>>> in either direction. >>>>> >>>> >>>> But the question had nothing to do with *other languages* it was a >>>> C/C++ example, and placing a Constant first has always been a nice >>>> habit to get into when doing comparisons, period. >>>> >>> >>> To prevent an ACCIDENTAL assignment. I understand that. And that is >>> the basic answer... >>> >>>> In the example the other operand was a function, so an error was >>>> likely in either case, but likely had nothing to do with the >>>> programmer employing the convention. >>>> >>>> And where did you get the idea you CAN NOT do an assignment in a >>>> conditional statement???? >>>> >>> >>> I didn't say you can't... I didn't even say you would want to. It is >>> just a common old C/C++ bug to ACCIDENTLY do an assignment. The >>> convention of constant first was simply to avoid that mistake. >>> >>> You can even do an assignent in C# and Java - it's jsut the result of >>> your expresion must be a boolean. >>> >>> string line; >>> while ((line = reader.ReadLine()) != null) >>> { >>> } >>> >>> >>> >>> -- >>> Tom Shelton >>> >>> >>> > > >
From: DanS on 22 Jul 2010 08:21 >>>>> It's C++ code.... Older C++ didn't define a bool type >>>>> or have any concept of a boolean value. That mades >>>>> these types of comparisons necessary, and the reverse >>>>> test was to prevent the old bug of accidently doing an >>>>> assignment in the test. >> >> LoopHere: >> >>>> Since when is a programmer's own deficiency a bug ? >>>> >>> A bug is any incorrect behavior in the program - which in >>> this old case maybe the result of a typo or as you say, >>> programmer deficiency. What does this actualy have to do >>> with my response? >> >> Why would you ask that ? >> >> Your response to the question was...... >> >> "Older C++ didn't define a bool type or have any concept >> of a boolean value. That mades these types of comparisons >> necessary, and the reverse test was to prevent the old bug >> of accidently doing an assignment in the test." >> >> Goto LoopHere; > > I'm w/ Tom in some surprise of even commenting on the use > of "bug" for the problem of a typo causing incorrect > behavior in code (in this case one instead of two "=" > signs). Would you not consider a misspelling of a variable > name or the inadvertent use of the wrong variable or any > number of other (more or less) mechanical mistakes bugs? > How would you define a bug vis a vis a "programmer > deficiency"? I don't know, I've never thought about it. I do know, however, that the times I've done an assignment vs. a compare, the code didn't work. (Yes, I know you, or I could give a 1000 examples of how it may work, yet still be incorrect.)
From: Bob Butler on 22 Jul 2010 08:38
"Tom Shelton" <tom_shelton(a)comcast.invalid> wrote in message news:i2852b$u82$1(a)news.eternal-september.org... > Bob Butler used his keyboard to write : >> "dpb" <none(a)non.net> wrote in message >> news:i27te9$ul$1(a)news.eternal-september.org... >> <cut> >>> I'm w/ Tom in some surprise of even commenting on the use of "bug" for >>> the problem of a typo causing incorrect behavior in code (in this case >>> one instead of two "=" signs). Would you not consider a misspelling of >>> a variable name or the inadvertent use of the wrong variable or any >>> number of other (more or less) mechanical mistakes bugs? How would you >>> define a bug vis a vis a "programmer deficiency"? >> >> It causes a bug in the application; it's not a bug in the language per >> se. > > No one said it was a bug in the language... Then I fail to understand what the question is about calling it a bug. If somebody codes if (x=0) { when they meant to code if (x==0) { then they have a bug in the code. |