Databases
StackOverflow2013
Postsdbo
POHow to use forward class declaration in a function with template?
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POHow to use forward class declaration in a function with template?
    primarykey
    data
    text
    <p>I have two classes. Each has a pointer pointing to the other class. So I have to use forward class declaration in one of them. This method runs well until I need to use a function with template (which I have to write both the declaration and implementation in the header file).</p> <p>More specifically, my codes are something like the following files. These files got compiled without problems on Windows by MS Visual Studio 2010. But when I compile them on Mac by XCode 4.3.2, I got an error of "Member access into incomplete type 'ClassB'" in file ClassA.h.</p> <p>Can anyone tell me how to make it compilable on Mac with XCode?</p> <p><strong>file ClassA.h</strong></p> <pre><code>#ifndef CLASS_A #define CLASS_A //#include "ClassB.h" class ClassB; class ClassA { public: ClassA(); template &lt;typename T&gt; void funcA(T *t); int iNum; ClassB *pB; }; template &lt;typename T&gt; void ClassA::funcA(T *t) { iNum = *(int*)t; iNum += pB-&gt;iNum; } #endif </code></pre> <p><strong>file ClassA.cpp</strong></p> <pre><code>#include "ClassA.h" ClassA::ClassA() { iNum = 1; } </code></pre> <p><strong>file ClassB.h</strong></p> <pre><code>#ifndef CLASS_B #define CLASS_B #include "ClassA.h" class ClassB { public: ClassB(); template &lt;typename T&gt; void funcB(T *t); int iNum; ClassA *pA; }; template &lt;typename T&gt; void ClassB::funcB(T *t) { iNum = *(int*)t; iNum -= pA-&gt;iNum; } #endif </code></pre> <p><strong>file ClassB.cpp</strong></p> <pre><code>#include "ClassB.h" ClassB::ClassB() { iNum = 2; } </code></pre> <p><strong>Main file</strong></p> <pre><code>#include &lt;stdio.h&gt; #include "ClassA.h" #include "ClassB.h" int main(void) { ClassA objA; ClassB objB; objA.pB = &amp;objB; objB.pA = &amp;objA; int a = 11; int b = 22; objA.funcA(&amp;a); objB.funcB(&amp;b); printf("Class A: %d, %d\n", objA.iNum, objA.pB-&gt;iNum); printf("Class B: %d, %d\n", objB.iNum, objB.pA-&gt;iNum); return 0; } </code></pre>
    singulars
    1. PO
      singulars
      1. PTAnswer
    1. This table or related slice is empty.
    1. PTQuestion
    1. This table or related slice is empty.
    1. USredpearl
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PO
      singulars
      1. PTAnswer
    1. VO
      singulars
      1. POHow to use forward class declaration in a function with template?
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. POHow to use forward class declaration in a function with template?
      1. USPiotrNycz
      1. VTFavorite
    3. VO
      singulars
      1. POHow to use forward class declaration in a function with template?
      1. This table or related slice is empty.
      1. VTUpMod
    1. COI got the same error on Linux. Our program is supposed to be able to run on all platforms, not only Windows. :(
      singulars
      1. POHow to use forward class declaration in a function with template?
      1. USredpearl
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload