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  3. C declarations are half backward

C declarations are half backward

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  • H Offline
    H Offline
    honey the codewitch
    wrote on last edited by
    #1

    Does it bother anyone else that you declare a pointer like:

    char* sz; // pointer type, pointer declared *with* type

    But an array is declared like this:

    char sz[1024];// array type, array declared *after* var name

    I think it's inconsistent, and I think the array specifier should have been declared with the type since it's essentially a type modifier like * and & Maybe it's just me?

    Real programmers use butterflies

    D S D R OriginalGriffO 20 Replies Last reply
    0
    • H honey the codewitch

      Does it bother anyone else that you declare a pointer like:

      char* sz; // pointer type, pointer declared *with* type

      But an array is declared like this:

      char sz[1024];// array type, array declared *after* var name

      I think it's inconsistent, and I think the array specifier should have been declared with the type since it's essentially a type modifier like * and & Maybe it's just me?

      Real programmers use butterflies

      D Offline
      D Offline
      DRHuff
      wrote on last edited by
      #2

      In both instances the first part declares the type, the second declares the variable. The array modifier is telling you how many of the type. Think of the first declaration as having a silent '[1]' and it becomes consistent. And you might be 40 years too late for bringing up this argument! :-D

      If you can't laugh at yourself - ask me and I will do it for you.

      H 1 Reply Last reply
      0
      • D DRHuff

        In both instances the first part declares the type, the second declares the variable. The array modifier is telling you how many of the type. Think of the first declaration as having a silent '[1]' and it becomes consistent. And you might be 40 years too late for bringing up this argument! :-D

        If you can't laugh at yourself - ask me and I will do it for you.

        H Offline
        H Offline
        honey the codewitch
        wrote on last edited by
        #3

        I guess that makes sense.

        DRHuff wrote:

        And you might be 40 years too late for bringing up this argument!

        At least!

        Real programmers use butterflies

        1 Reply Last reply
        0
        • H honey the codewitch

          Does it bother anyone else that you declare a pointer like:

          char* sz; // pointer type, pointer declared *with* type

          But an array is declared like this:

          char sz[1024];// array type, array declared *after* var name

          I think it's inconsistent, and I think the array specifier should have been declared with the type since it's essentially a type modifier like * and & Maybe it's just me?

          Real programmers use butterflies

          S Offline
          S Offline
          swampwiz
          wrote on last edited by
          #4

          What has bothered me more is the fact that: int* pa; int *pa; are the same. Had I been Bjorn, I wouldn't have allowed the latter.

          H L Mike HankeyM J 4 Replies Last reply
          0
          • S swampwiz

            What has bothered me more is the fact that: int* pa; int *pa; are the same. Had I been Bjorn, I wouldn't have allowed the latter.

            H Offline
            H Offline
            honey the codewitch
            wrote on last edited by
            #5

            I can see why but on the other hand I don't like the idea of significant whitespace between tokens in language. It's one of the reasons I don't like Python.

            Real programmers use butterflies

            1 Reply Last reply
            0
            • H honey the codewitch

              Does it bother anyone else that you declare a pointer like:

              char* sz; // pointer type, pointer declared *with* type

              But an array is declared like this:

              char sz[1024];// array type, array declared *after* var name

              I think it's inconsistent, and I think the array specifier should have been declared with the type since it's essentially a type modifier like * and & Maybe it's just me?

              Real programmers use butterflies

              D Offline
              D Offline
              Daniel Pfeffer
              wrote on last edited by
              #6

              They are literally half backward. In order to understand a C type definition, you ping-pong between the part before the name and the part after, until all tokens have been processed. X| If there is one single thing for K&R ought to have been taken out and shot, this is it! :|

              Freedom is the freedom to say that two plus two make four. If that is granted, all else follows. -- 6079 Smith W.

              1 Reply Last reply
              0
              • H honey the codewitch

                Does it bother anyone else that you declare a pointer like:

                char* sz; // pointer type, pointer declared *with* type

                But an array is declared like this:

                char sz[1024];// array type, array declared *after* var name

                I think it's inconsistent, and I think the array specifier should have been declared with the type since it's essentially a type modifier like * and & Maybe it's just me?

                Real programmers use butterflies

                R Offline
                R Offline
                RickZeeland
                wrote on last edited by
                #7

                Let it Rust! :-\

                1 Reply Last reply
                0
                • H honey the codewitch

                  Does it bother anyone else that you declare a pointer like:

                  char* sz; // pointer type, pointer declared *with* type

                  But an array is declared like this:

                  char sz[1024];// array type, array declared *after* var name

                  I think it's inconsistent, and I think the array specifier should have been declared with the type since it's essentially a type modifier like * and & Maybe it's just me?

                  Real programmers use butterflies

                  OriginalGriffO Offline
                  OriginalGriffO Offline
                  OriginalGriff
                  wrote on last edited by
                  #8

                  The usage is odd as well:

                  char* p = ...
                  *p = 'x';

                  Vs

                  foo f;
                  foo *pf = &f;
                  f.x = '?';
                  pf->x = '!';

                  Why invent two access operators "." and "->", when you could just use "*pf.x" and be more consistent? Or use "->" to dereference all pointers? I get the feeling bits of the C spec were thrown in just before the submission deadline ... :laugh:

                  "I have no idea what I did, but I'm taking full credit for it." - ThisOldTony "Common sense is so rare these days, it should be classified as a super power" - Random T-shirt AntiTwitter: @DalekDave is now a follower!

                  "I have no idea what I did, but I'm taking full credit for it." - ThisOldTony
                  "Common sense is so rare these days, it should be classified as a super power" - Random T-shirt

                  D M 2 Replies Last reply
                  0
                  • OriginalGriffO OriginalGriff

                    The usage is odd as well:

                    char* p = ...
                    *p = 'x';

                    Vs

                    foo f;
                    foo *pf = &f;
                    f.x = '?';
                    pf->x = '!';

                    Why invent two access operators "." and "->", when you could just use "*pf.x" and be more consistent? Or use "->" to dereference all pointers? I get the feeling bits of the C spec were thrown in just before the submission deadline ... :laugh:

                    "I have no idea what I did, but I'm taking full credit for it." - ThisOldTony "Common sense is so rare these days, it should be classified as a super power" - Random T-shirt AntiTwitter: @DalekDave is now a follower!

                    D Offline
                    D Offline
                    Daniel Pfeffer
                    wrote on last edited by
                    #9

                    Quote:

                    Why do we do this? I'll tell you... I don't know. But because of this, every one of us knows what a pointer is, how to dereference it, and what K&R expect of him.

                    With apologies to Sholem Aleichem and to the producers of Fiddler on the Roof :)

                    Freedom is the freedom to say that two plus two make four. If that is granted, all else follows. -- 6079 Smith W.

                    W 1 Reply Last reply
                    0
                    • H honey the codewitch

                      Does it bother anyone else that you declare a pointer like:

                      char* sz; // pointer type, pointer declared *with* type

                      But an array is declared like this:

                      char sz[1024];// array type, array declared *after* var name

                      I think it's inconsistent, and I think the array specifier should have been declared with the type since it's essentially a type modifier like * and & Maybe it's just me?

                      Real programmers use butterflies

                      L Offline
                      L Offline
                      Lost User
                      wrote on last edited by
                      #10

                      If you read it in reverse it can make more sense:

                      // extra space before asterisk for readability (I never use it)
                      char * sz; // sz is a pointer to a character variable

                      char sz[1024]; // sz is an array of character types

                      H V 2 Replies Last reply
                      0
                      • S swampwiz

                        What has bothered me more is the fact that: int* pa; int *pa; are the same. Had I been Bjorn, I wouldn't have allowed the latter.

                        L Offline
                        L Offline
                        Lost User
                        wrote on last edited by
                        #11

                        But you can also write:

                        int*pa;
                        int * pa;

                        the spaces do not affect the binding. And that was the rule way before the great Stroustrup.

                        1 Reply Last reply
                        0
                        • H honey the codewitch

                          Does it bother anyone else that you declare a pointer like:

                          char* sz; // pointer type, pointer declared *with* type

                          But an array is declared like this:

                          char sz[1024];// array type, array declared *after* var name

                          I think it's inconsistent, and I think the array specifier should have been declared with the type since it's essentially a type modifier like * and & Maybe it's just me?

                          Real programmers use butterflies

                          Sander RosselS Offline
                          Sander RosselS Offline
                          Sander Rossel
                          wrote on last edited by
                          #12

                          char* means you should read the footnote. * array declarations in C may or may not be consistent.

                          Best, Sander Azure DevOps Succinctly (free eBook) Azure Serverless Succinctly (free eBook) Migrating Apps to the Cloud with Azure arrgh.js - Bringing LINQ to JavaScript

                          1 Reply Last reply
                          0
                          • L Lost User

                            If you read it in reverse it can make more sense:

                            // extra space before asterisk for readability (I never use it)
                            char * sz; // sz is a pointer to a character variable

                            char sz[1024]; // sz is an array of character types

                            H Offline
                            H Offline
                            honey the codewitch
                            wrote on last edited by
                            #13

                            The floating asterisk looks lonely!

                            Real programmers use butterflies

                            1 Reply Last reply
                            0
                            • H honey the codewitch

                              Does it bother anyone else that you declare a pointer like:

                              char* sz; // pointer type, pointer declared *with* type

                              But an array is declared like this:

                              char sz[1024];// array type, array declared *after* var name

                              I think it's inconsistent, and I think the array specifier should have been declared with the type since it's essentially a type modifier like * and & Maybe it's just me?

                              Real programmers use butterflies

                              V Offline
                              V Offline
                              Vikram A Punathambekar
                              wrote on last edited by
                              #14

                              I wrote this in a previous life: [How to interpret complex C/C++ declarations](https://www.codeproject.com/Articles/7042/How-to-interpret-complex-C-C-declarations)

                              Cheers, विक्रम "We have already been through this, I am not going to repeat myself." - fat_boy, in a global warming thread :doh:

                              1 Reply Last reply
                              0
                              • L Lost User

                                If you read it in reverse it can make more sense:

                                // extra space before asterisk for readability (I never use it)
                                char * sz; // sz is a pointer to a character variable

                                char sz[1024]; // sz is an array of character types

                                V Offline
                                V Offline
                                Vikram A Punathambekar
                                wrote on last edited by
                                #15

                                There's a stricter formal rule, called the Right-Left rule. I wrote my only technical article on CP more than 15 years back on just this: [How to interpret complex C/C++ declarations](https://www.codeproject.com/Articles/7042/How-to-interpret-complex-C-C-declarations)

                                Cheers, विक्रम "We have already been through this, I am not going to repeat myself." - fat_boy, in a global warming thread :doh:

                                L 1 Reply Last reply
                                0
                                • V Vikram A Punathambekar

                                  There's a stricter formal rule, called the Right-Left rule. I wrote my only technical article on CP more than 15 years back on just this: [How to interpret complex C/C++ declarations](https://www.codeproject.com/Articles/7042/How-to-interpret-complex-C-C-declarations)

                                  Cheers, विक्रम "We have already been through this, I am not going to repeat myself." - fat_boy, in a global warming thread :doh:

                                  L Offline
                                  L Offline
                                  Lost User
                                  wrote on last edited by
                                  #16

                                  Yes, but I could not remember it. I know it's important when typedef'ing function pointers. I just reread your article - very interesting, and should be required reading for all the QA kiddies.

                                  1 Reply Last reply
                                  0
                                  • S swampwiz

                                    What has bothered me more is the fact that: int* pa; int *pa; are the same. Had I been Bjorn, I wouldn't have allowed the latter.

                                    Mike HankeyM Online
                                    Mike HankeyM Online
                                    Mike Hankey
                                    wrote on last edited by
                                    #17

                                    Agree, the later makes no sense.

                                    I'm not sure how many cookies it makes to be happy, but so far it's not 27. JaxCoder.com

                                    1 Reply Last reply
                                    0
                                    • H honey the codewitch

                                      Does it bother anyone else that you declare a pointer like:

                                      char* sz; // pointer type, pointer declared *with* type

                                      But an array is declared like this:

                                      char sz[1024];// array type, array declared *after* var name

                                      I think it's inconsistent, and I think the array specifier should have been declared with the type since it's essentially a type modifier like * and & Maybe it's just me?

                                      Real programmers use butterflies

                                      P Offline
                                      P Offline
                                      PIEBALDconsult
                                      wrote on last edited by
                                      #18

                                      And?

                                      1 Reply Last reply
                                      0
                                      • H honey the codewitch

                                        Does it bother anyone else that you declare a pointer like:

                                        char* sz; // pointer type, pointer declared *with* type

                                        But an array is declared like this:

                                        char sz[1024];// array type, array declared *after* var name

                                        I think it's inconsistent, and I think the array specifier should have been declared with the type since it's essentially a type modifier like * and & Maybe it's just me?

                                        Real programmers use butterflies

                                        T Offline
                                        T Offline
                                        theoldfool
                                        wrote on last edited by
                                        #19

                                        Stop whining. :) Declarations made easy. Computer Language Magazine, May, 1991.

                                        If you can keep your head while those about you are losing theirs, perhaps you don't understand the situation.

                                        1 Reply Last reply
                                        0
                                        • H honey the codewitch

                                          Does it bother anyone else that you declare a pointer like:

                                          char* sz; // pointer type, pointer declared *with* type

                                          But an array is declared like this:

                                          char sz[1024];// array type, array declared *after* var name

                                          I think it's inconsistent, and I think the array specifier should have been declared with the type since it's essentially a type modifier like * and & Maybe it's just me?

                                          Real programmers use butterflies

                                          M Offline
                                          M Offline
                                          Mike Winiberg
                                          wrote on last edited by
                                          #20

                                          Without wishing to start a major language debate, I think its important to understand that C was designed to be efficient at using the underlying hardware of the machine, and the way things are declared reflects this: char *sz declares a single variable that points to a place in memory, supposedly holding a char value. This pointer (and here's where dragons lie!) can be made to point to anywhere and to anything regardless of its declaration, you are just telling the compiler that at the place where that pointer points, YOU consider there to be a char value (whether it is or not in reality). char sz[1024] says that at the address represented by sz is a reserved block of memory that holds (in theory) 1024 char items. In your code you can (with some severe caveats!) use both variables in the same way and it's up to you to remember and manage whatever you think you are looking at in that location - this is both the beauty and danger of a language like C - it allows you to manipulate things in much the same way as in assembler and with as few restrictions, but it provides no protection against you doing something stupid. However, even the early compilers would detect if you attempted to treat these two variables as exactly equivalent, but would often only warn rather than prevent it, allowing you to create absolute havoc. Much code rot is caused by the developer incorrectly assuming that, by default, either of these variables is initialised (which is why most compilers these days will attempt to put something sensible in newly declared variables to protect the innocent). Before initialisation char *sz may contain a random address and even attempting to look at it might cause a total system crash if it accidentally points into hardware protected memory. With char sz[1024] though you can be sure that doing char x = *sz is safe because sz already holds a valid address and points into memory allocated to your program, what you don't know is what value you will actually get back from that place before the array is initialised. Why have I bored you all with this stuff? Because so many developers these days seem to know absolutely nothing at all about how the hardware they are driving works - that's fine if you are writing in a high-level domain specific language where everything like that is hidden - no help at all if you are writing a device driver for some complex piece of hardware that is integrated into an operating system of some sort.

                                          H W 2 Replies Last reply
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