struct, typedef, and template

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  • Ed
    #1

    struct, typedef, and template

    Hi, guys,
    In C language manner, we need to put a "struct" token before one
    struct variable declaration like following.

    <code>
    struct Apple
    {
    float Price;
    };

    struct Apple apple;
    </code>

    Sometime, we would use typedef to simplify the usage.

    <code>
    typedef struct _Apple
    {
    float Price;
    } Apple;

    Apple apple;
    </code>


    Now, when we use this manner in C++, it seems we don't need to add a
    typedef for the struct declaration.

    <code>
    struct Apple
    {
    float Price;
    };

    Apple apple;
    </code>

    Directly using "Apple" to do the declaration is OK in VS compiler and
    Intel Compiler.
    My question is should I still keep the usage of old struct usage.

    Why I ask this question is because of template.
    I write a template struct.


    template <typename Real>
    struct Vector
    {
    Real x;
    Real y;
    Real z;
    };

    Vector<floatvec tor;

    You know that we can not add a typedef to a template struct. So, I am
    wondering if this is OK.

    Thanks!
    Ed.






    Tags: None
    • Ian Collins
      #2
      Re: struct, typedef, and template

      Ed wrote:
      Hi, guys,
      In C language manner, we need to put a "struct" token before one
      struct variable declaration like following.
      >
      <code>
      struct Apple
      {
      float Price;
      };
      >
      struct Apple apple;
      </code>
      >
      Now, when we use this manner in C++, it seems we don't need to add a
      typedef for the struct declaration.
      >
      Correct. In C++, struts and classes are types.

      --
      Ian Collins.

        Comment

        • Ed
          #3
          Re: struct, typedef, and template

          On Aug 25, 4:45 pm, Ian Collins <ian-n...@hotmail.co mwrote:
          Ed wrote:
          Hi, guys,
          In C language manner, we need to put a "struct" token before one
          struct variable declaration like following.
          >
          <code>
          struct Apple
          {
             float Price;
          };
          >
          struct Apple apple;
          </code>
          >
          Now, when we use this manner in C++, it seems we don't need to add a
          typedef for the struct declaration.
          >
          Correct.  In C++, struts and classes are types.
          >
          --
          Ian Collins.
          Is this the rule in C++ standard?


            Comment

            • =?utf-8?Q?David_C=C3=B4me?=
              #4
              Re: struct, typedef, and template

              On Mon, 25 Aug 2008 11:00:37 +0200, Ed <seahalo@gmail. comwrote:
              On Aug 25, 4:45 pm, Ian Collins <ian-n...@hotmail.co mwrote:
              >Ed wrote:
              Hi, guys,
              In C language manner, we need to put a "struct" token before one
              struct variable declaration like following.
              >>
              <code>
              struct Apple
              {
                 float Price;
              };
              >>
              struct Apple apple;
              </code>
              >>
              Now, when we use this manner in C++, it seems we don't need to add a
              typedef for the struct declaration.
              >>
              >Correct.  In C++, struts and classes are types.
              >>
              >--
              >Ian Collins.
              >
              Is this the rule in C++ standard?
              >
              Yep.

                Comment

                • Rolf Magnus
                  #5
                  Re: struct, typedef, and template

                  Ed wrote:
                  Directly using "Apple" to do the declaration is OK in VS compiler and
                  Intel Compiler.
                  It's standard C++.
                  My question is should I still keep the usage of old struct usage.
                  Only for those parts of your code that might need to be used from C code.
                  Why I ask this question is because of template.
                  I write a template struct.
                  >
                  >
                  template <typename Real>
                  struct Vector
                  {
                  Real x;
                  Real y;
                  Real z;
                  };
                  >
                  Vector<floatvec tor;
                  >
                  You know that we can not add a typedef to a template struct. So, I am
                  wondering if this is OK.
                  Yes.


                    Comment

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