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  3. for those of you purists that don't like break, continue and goto

for those of you purists that don't like break, continue and goto

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  • H honey the codewitch

    why do this?

    for(int i = 0;i
    instead of

    for(int i = 0;i

    hengh?? why you still use break?

    :laugh:

    When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.

    L Offline
    L Offline
    Lost User
    wrote on last edited by
    #27

    I have even encountered this in pseudocode, where the author could easily have added a `break` to his made-up exposition-purposes-only language but chose a more obfuscated way instead.

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    • N Nand32

      At times, the purpose of the search might be just to find the index of the valueToFind. Break keeps the index safe?

      (JS)
      var arr =[0,1,2,3,4,5];
      var valueToFind = 3;

      for(i=0;i

      H Offline
      H Offline
      honey the codewitch
      wrote on last edited by
      #28

      right, but in the OP i limited i to the loop scope, but yeah.

      When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.

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      • H honey the codewitch

        why do this?

        for(int i = 0;i
        instead of

        for(int i = 0;i

        hengh?? why you still use break?

        :laugh:

        When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.

        N Offline
        N Offline
        Night Fox Localhost
        wrote on last edited by
        #29

        I prefer break statements. It is not suitable for big projects it might be confusing. I try my level best to write clean code!

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        • H honey the codewitch

          why do this?

          for(int i = 0;i
          instead of

          for(int i = 0;i

          hengh?? why you still use break?

          :laugh:

          When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.

          G Offline
          G Offline
          Gary R Wheeler
          wrote on last edited by
          #30

          Because the second fragment duplicates knowledge of the loop's termination condition. You have to remember to adjust it in two places. The first fragment is therefore more robust.

          Software Zen: delete this;

          H 1 Reply Last reply
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          • G Gary R Wheeler

            Because the second fragment duplicates knowledge of the loop's termination condition. You have to remember to adjust it in two places. The first fragment is therefore more robust.

            Software Zen: delete this;

            H Offline
            H Offline
            honey the codewitch
            wrote on last edited by
            #31

            yep. although there are cases where I'll modify i inside the loop for other reasons. Like if I have to add or remove items while enumerating (it happens with complicated algos)

            When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.

            G 1 Reply Last reply
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            • H honey the codewitch

              why do this?

              for(int i = 0;i
              instead of

              for(int i = 0;i

              hengh?? why you still use break?

              :laugh:

              When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.

              L Offline
              L Offline
              Lost User
              wrote on last edited by
              #32

              Yours is BS because it will execute everything after the if.

              H 1 Reply Last reply
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              • L Lost User

                Yours is BS because it will execute everything after the if.

                H Offline
                H Offline
                honey the codewitch
                wrote on last edited by
                #33

                It was sample code. Normally you'd account for that when you put actual code in there, but without putting anything in there, it's not for me to know where the actual break should happen. However, it was sort of written with the idea that it would follow the main loop logic, kind of like the break example would. Of course the control flow is slightly different, but it's not irreconcilably different. if you need something to go after the conditional check, you'd wrap whatever went after the break in the one example in an else block instead.

                When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.

                L 1 Reply Last reply
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                • H honey the codewitch

                  It was sample code. Normally you'd account for that when you put actual code in there, but without putting anything in there, it's not for me to know where the actual break should happen. However, it was sort of written with the idea that it would follow the main loop logic, kind of like the break example would. Of course the control flow is slightly different, but it's not irreconcilably different. if you need something to go after the conditional check, you'd wrap whatever went after the break in the one example in an else block instead.

                  When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.

                  L Offline
                  L Offline
                  Lost User
                  wrote on last edited by
                  #34

                  Yeas it the simpliest possible 5 lines code. In real life you would probably have another couple of hundreds lines of similar mess entagled there, with some poor soul wondering why is this piece of crap executing when it was not supposed to.

                  H 1 Reply Last reply
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                  • L Lost User

                    Yeas it the simpliest possible 5 lines code. In real life you would probably have another couple of hundreds lines of similar mess entagled there, with some poor soul wondering why is this piece of crap executing when it was not supposed to.

                    H Offline
                    H Offline
                    honey the codewitch
                    wrote on last edited by
                    #35

                    :laugh: it's funny cuz it's true. For the record, I'm not endorsing the method i described, I'm simply being facetious about it. I think it's silly. A break statement is much clearer, which was kind of the point of my OP. Sometimes you need break. Or a continue. Or even a goto (which i can give a solid use case for - in this case making the code MORE readable)

                    When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.

                    L 1 Reply Last reply
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                    • H honey the codewitch

                      :laugh: it's funny cuz it's true. For the record, I'm not endorsing the method i described, I'm simply being facetious about it. I think it's silly. A break statement is much clearer, which was kind of the point of my OP. Sometimes you need break. Or a continue. Or even a goto (which i can give a solid use case for - in this case making the code MORE readable)

                      When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.

                      L Offline
                      L Offline
                      Lost User
                      wrote on last edited by
                      #36

                      Alright, here a piece of advice: never exit conditionally a for cycle. if you need to do that, use while or do until.

                      H 1 Reply Last reply
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                      • L Lost User

                        Alright, here a piece of advice: never exit conditionally a for cycle. if you need to do that, use while or do until.

                        H Offline
                        H Offline
                        honey the codewitch
                        wrote on last edited by
                        #37

                        i think it depends on the situation for example

                        public int IndexOf(T item)
                        {
                        var ic = Count;
                        var i = 0;
                        for(;i

                        That's very clear even without comments

                        When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.

                        L 1 Reply Last reply
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                        • H honey the codewitch

                          i think it depends on the situation for example

                          public int IndexOf(T item)
                          {
                          var ic = Count;
                          var i = 0;
                          for(;i

                          That's very clear even without comments

                          When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.

                          L Offline
                          L Offline
                          Lost User
                          wrote on last edited by
                          #38

                          i=-1 do i++ until Equals(item,this[i]) return i

                          H 1 Reply Last reply
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                          • L Lost User

                            i=-1 do i++ until Equals(item,this[i]) return i

                            H Offline
                            H Offline
                            honey the codewitch
                            wrote on last edited by
                            #39

                            i mean yeah. That's a little less clear to me though. I avoid do loops usually because the conditional can get confusing if you're used to regular for loops. It takes me a second to work out what's going on, like when exactly the condition exits. It's not big deal, it's just my preference. I think my code is clearer.

                            When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.

                            L 1 Reply Last reply
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                            • H honey the codewitch

                              i mean yeah. That's a little less clear to me though. I avoid do loops usually because the conditional can get confusing if you're used to regular for loops. It takes me a second to work out what's going on, like when exactly the condition exits. It's not big deal, it's just my preference. I think my code is clearer.

                              When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.

                              L Offline
                              L Offline
                              Lost User
                              wrote on last edited by
                              #40

                              It is simpler and I actually use pretty much exactly the same code when it is that simple. When you have more than a page of lines within that loop a sudden exit is not what I would do. And a sudden conditional exit with break or return might be even ok. Putting the i to the max and then exit in that manner is something I would never do.

                              H 1 Reply Last reply
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                              • L Lost User

                                It is simpler and I actually use pretty much exactly the same code when it is that simple. When you have more than a page of lines within that loop a sudden exit is not what I would do. And a sudden conditional exit with break or return might be even ok. Putting the i to the max and then exit in that manner is something I would never do.

                                H Offline
                                H Offline
                                honey the codewitch
                                wrote on last edited by
                                #41

                                well to each their own. probably it also has to do with my C++ background which influences a lot of my code. Not that C++ has different flow constructs, it's just that a) i learned these habits a long time ago and the industry changes b) C++ development is a different animal, and control flow is all over the place generally and for loops are used for almost everything except while(true) although some people go for(;;). It's not uncommon even to do stuff like for(current=firstNode;null!=current;current=current.nextNode) if(current->key==key) break; to traverse a linked list for example.

                                When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.

                                1 Reply Last reply
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                                • H honey the codewitch

                                  yep. although there are cases where I'll modify i inside the loop for other reasons. Like if I have to add or remove items while enumerating (it happens with complicated algos)

                                  When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.

                                  G Offline
                                  G Offline
                                  Gary R Wheeler
                                  wrote on last edited by
                                  #42

                                  That makes sense, especially given the type of algorithms you deal with in parsers and data structures. In the course of developing several large, complex applications, I've learned that having pieces of code that must stay in sync logically or follow the same algorithm is a failure point. Refactoring can help if i makes sense to move things into a method, and then have each location invoke the method. The hard part there can be figuring out a name for the thing: "CheckToSeeIfMessageNeededAtThreadExit" is ugly :-D.

                                  Software Zen: delete this;

                                  H 1 Reply Last reply
                                  0
                                  • G Gary R Wheeler

                                    That makes sense, especially given the type of algorithms you deal with in parsers and data structures. In the course of developing several large, complex applications, I've learned that having pieces of code that must stay in sync logically or follow the same algorithm is a failure point. Refactoring can help if i makes sense to move things into a method, and then have each location invoke the method. The hard part there can be figuring out a name for the thing: "CheckToSeeIfMessageNeededAtThreadExit" is ugly :-D.

                                    Software Zen: delete this;

                                    H Offline
                                    H Offline
                                    honey the codewitch
                                    wrote on last edited by
                                    #43

                                    right. Extract Method is one of my favorite refactoring tools I don't use incredibly long names for private methods. I'll abbreviate something like the above to _CheckMessageThread() Public members i usually go all out, and give it a really long name if it needs one.

                                    When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.

                                    1 Reply Last reply
                                    0
                                    • H honey the codewitch

                                      why do this?

                                      for(int i = 0;i
                                      instead of

                                      for(int i = 0;i

                                      hengh?? why you still use break?

                                      :laugh:

                                      When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.

                                      S Offline
                                      S Offline
                                      SwitcherSoft
                                      wrote on last edited by
                                      #44

                                      A purist should be worried about touching control variables. Hmmm.

                                      Jordan

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                                      • H honey the codewitch

                                        ugh, VB. I use goto in some of my code. Perfectly acceptable place to use GOTO - generated state machine code:

                                        public static bool AcceptsByte(Grimoire.ParseContext pc)
                                        {
                                        pc.EnsureStarted();
                                        if (-1 == pc.Current) return false;
                                        if ((48 == pc.Current))
                                        {
                                        pc.Advance();
                                        goto AcceptsByte_s1;
                                        }
                                        if ((49 == pc.Current))
                                        {
                                        pc.Advance();
                                        goto AcceptsByte_s2;
                                        }
                                        if ((50 == pc.Current))
                                        {
                                        pc.Advance();
                                        goto AcceptsByte_s4;
                                        }
                                        if ((51 <= pc.Current && 57 >= pc.Current))
                                        {
                                        pc.Advance();
                                        goto AcceptsByte_s3;
                                        }
                                        return false;
                                        AcceptsByte_s1:
                                        if (-1 == pc.Current) return true;
                                        return -1 == pc.Advance();
                                        AcceptsByte_s2:
                                        if (-1 == pc.Current) return true;
                                        if ((48 <= pc.Current && 57 >= pc.Current))
                                        {
                                        pc.Advance();
                                        goto AcceptsByte_s3;
                                        }
                                        return -1 == pc.Advance();
                                        AcceptsByte_s3:
                                        if (-1 == pc.Current) return true;
                                        if ((48 <= pc.Current && 57 >= pc.Current))
                                        {
                                        pc.Advance();
                                        goto AcceptsByte_s1;
                                        }
                                        return -1 == pc.Advance();
                                        AcceptsByte_s4:
                                        if (-1 == pc.Current) return true;
                                        if ((48 <= pc.Current && 52 >= pc.Current))
                                        {
                                        pc.Advance();
                                        goto AcceptsByte_s3;
                                        }
                                        if ((53 == pc.Current))
                                        {
                                        pc.Advance();
                                        goto AcceptsByte_s5;
                                        }
                                        if ((54 <= pc.Current && 57 >= pc.Current))
                                        {
                                        pc.Advance();
                                        goto AcceptsByte_s1;
                                        }
                                        return -1 == pc.Advance();
                                        AcceptsByte_s5:
                                        if (-1 == pc.Current) return true;
                                        if ((48 <= pc.Current && 52 >= pc.Current))
                                        {
                                        pc.Advance();
                                        goto AcceptsByte_s1;
                                        }
                                        return -1 == pc.Advance();
                                        }

                                        but then I wouldn't write that code by hand. Too error prone.

                                        When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.

                                        J Offline
                                        J Offline
                                        John Brett
                                        wrote on last edited by
                                        #45

                                        Quote:

                                        but then I wouldn't write that code by hand. Too error prone.

                                        Isn't this exactly the point? All code gets compiled/interpreted/translated to jmps eventually. The goals of the written code should be correctness, understandability and simplicity. Leave the gotos and the clever techniques to the compiler.

                                        A H 2 Replies Last reply
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                                        • L Lost User

                                          throw would be even more clear, definite and failure proof. (well I do see many kids using exactly that to 'not use goto endlabel')

                                          Message Signature (Click to edit ->)

                                          K Offline
                                          K Offline
                                          kalberts
                                          wrote on last edited by
                                          #46

                                          If finding the desired value is exceptional and unexpected and requiring special handling, then throwing an exception is appropriate. If it is the normal and desired case, exeactly what you expected: "Yeah, there it is!", then an exception is not the right mechanism.

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