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???
01/01/11 20:29
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 		 #180389 - Pointers and type-safety
Responding to: ???'s previous message
Andy Neil said:
Per Westermark said:
until Turbo Pascal, you didn't had a chance to play with pointer types.

Not true: I have here before me the original "Pascal User Manual & Report" by Jensen & Wirth (the "K&R" of Pascal) - and there is a whole chapter on Pointer Types!

You couldn't typecast a pointer from one type to another, except for some very specific cases.

Turbo Pascal worked a lot with typecasts and also had a "void" pointer type, and an address-of operator, removing the type safe protection Pascal was designed with, but instead allowing it to solve systems-related problems. I think the extensions are available in Free Pascal too. And you got some basic forms of pointer arithmetic too.

Andy Neil said:
But you still get null pointer exceptions, which is a very common failure for .NET and Java applications.

Isn't that because they are actually C/C++ "under the hood"...?

No, a reference is a special form of a pointer that is defined to either point at NULL, or a valid object.

The funny thing is just that they have spent a lot of time explicitly telling that the languages don't have pointers, but they did select the word "pointer" in the error message. Not sure if it was intentional, to "protect" their magic references from getting any blame ;)

List of 76 messages in thread
TopicAuthorDate
Partial decoding of external memory...            01/01/70 00:00      
   8 bit DATA Space            01/01/70 00:00      
      aka "PDATA"            01/01/70 00:00      
   Adres Latch            01/01/70 00:00      
      corrections to all the above replies            01/01/70 00:00      
         Partial decoding of external memory...            01/01/70 00:00      
            There are two locations in the LCD            01/01/70 00:00      
               Re: There are two locations in the LCD            01/01/70 00:00      
                  timing is the reason ...            01/01/70 00:00      
                     one fact expanded            01/01/70 00:00      
                     Thanks for the advice...            01/01/70 00:00      
                        still?            01/01/70 00:00      
                        Maybe it wouldn't hurt to spend time reading the datasheet            01/01/70 00:00      
                           Checking out the Datasheets...            01/01/70 00:00      
                              That's interesting ...            01/01/70 00:00      
                                 Not all BASIC are the same            01/01/70 00:00      
                                    does that apply to BASCOM?            01/01/70 00:00      
                                       "improvements" or extensions?            01/01/70 00:00      
                                          Modern versions of BASIC            01/01/70 00:00      
                                 Re: That's interesting ...            01/01/70 00:00      
                                    Programming on the Fringe            01/01/70 00:00      
                                       Re: Programming on the Fringe            01/01/70 00:00      
                                          To PC or not - but avoid dead ends            01/01/70 00:00      
                                          I'd recommend you think some more about all that            01/01/70 00:00      
                                             That's the key!            01/01/70 00:00      
                                             Brain pollution            01/01/70 00:00      
                                                re: teaching language            01/01/70 00:00      
                                                   Introduce a computer or introduce how to program            01/01/70 00:00      
                                                Initial attraction is fundamental flaw            01/01/70 00:00      
                                    Which concepts do you find particularly hard to grasp?            01/01/70 00:00      
                                       Pointers are normally the main problem when learning C            01/01/70 00:00      
                                          Is the problem specifically 'C', though?            01/01/70 00:00      
                                          pointers aren't unique to 'C'            01/01/70 00:00      
                                             Pointers            01/01/70 00:00      
                                             Big difference in concept - C actually unusual            01/01/70 00:00      
                                                Remember PEEK and POKE            01/01/70 00:00      
                                                Pointers            01/01/70 00:00      
                                                   Pointers and type-safety            01/01/70 00:00      
                                          big problems            01/01/70 00:00      
                                             Wrong direction            01/01/70 00:00      
                                                goes both ways            01/01/70 00:00      
                                       Re: Which concepts do you find particularly hard to grasp?            01/01/70 00:00      
                                          Not a casual subject            01/01/70 00:00      
                                             Re: Not a casual subject            01/01/70 00:00      
                                                I think it's already been said in this thread...            01/01/70 00:00      
                                                one C book should do            01/01/70 00:00      
                                                   Manzi?            01/01/70 00:00      
                                                   It might not hurt to do this in a different sequence            01/01/70 00:00      
                                                   Re: one C book should do            01/01/70 00:00      
                                                      Language matters            01/01/70 00:00      
                                                      you haven't seen ...            01/01/70 00:00      
                                                         Yes, but...            01/01/70 00:00      
                                                            Languages helps but isn't enough            01/01/70 00:00      
                                                         Re: you haven't seen ...            01/01/70 00:00      
                                                            RE: been looking at snippets            01/01/70 00:00      
                                                               Re: been looking at snippets            01/01/70 00:00      
                                                                  Details in standard + compiler manual            01/01/70 00:00      
                                                                      a book doesn't detail everything            01/01/70 00:00      
                                                                     You need to study the compiler documentation            01/01/70 00:00      
                                                                        You need to lean the language first!            01/01/70 00:00      
                                                                           my point was ...            01/01/70 00:00      
                                                                        Re: You need to study the compiler documentation            01/01/70 00:00      
                                                                           Go directly for C            01/01/70 00:00      
                                                                              i second this            01/01/70 00:00      
                                                                              Re: Go Directly to C            01/01/70 00:00      
                                                                                 C support            01/01/70 00:00      
                                                                           the big advantage of PASCAL is            01/01/70 00:00      
                                                                              C isn't that dangerous if caring for compiler warnings            01/01/70 00:00      
                                                                                 So ... C++ is not of interest in this context            01/01/70 00:00      
                                                                                    It's about bracketing claims            01/01/70 00:00      
                                                                                       I did say, "in this context", didn't I?            01/01/70 00:00      
                                                                                          Be careful with your asides!            01/01/70 00:00      
                                                                                          Always give enough context to statements            01/01/70 00:00      
                                                                                             OK ... I stand corrected            01/01/70 00:00      
                                                                                                Separate thread!            01/01/70 00:00      
                                                                                                   I hoped someone would do that            01/01/70 00:00      

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