Databases
StackOverflow2013
Postsdbo
POSpecific Template Friendship in C++
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POSpecific Template Friendship in C++
    primarykey
    data
    text
    <p>I have a question for Specific Template Friendship in C++. in the book C++ Primer, the specific template friendship is written like this:</p> <pre><code> template &lt;class T&gt; class Foo3; template &lt;class T&gt; void templ_fcn3(const T&amp;); template &lt;class Type&gt; class Bar { // each instantiation of Bar grants access to the // version of Foo3 or templ_fcn3 instantiated with the same type friend class Foo3&lt;Type&gt;; friend void templ_fcn3&lt;Type&gt;(const Type&amp;); // ... }; </code></pre> <p>The special point is that there is </p> <pre><code>&lt;Type&gt; </code></pre> <p>after the class or function name in the <strong>friend</strong> statement.</p> <p>However,in practice, if I write this:</p> <pre><code>template &lt;class Type&gt; class T_CheckPointer; template &lt;class T&gt; T_CheckPointer&lt;T&gt; operator+(const T_CheckPointer&lt;T&gt; &amp;, const size_t n); template &lt;typename Type&gt; class T_CheckPointer { // Specific Template Friendship friend T_CheckPointer&lt;Type&gt; operator+ &lt;Type&gt; (const T_CheckPointer&lt;Type&gt; &amp;, const size_t n); // other code... } </code></pre> <p>There will be a error during instantiations for the template function.</p> <p>And if I change </p> <pre><code>// Specific Template Friendship friend T_CheckPointer&lt;Type&gt; operator+ &lt;Type&gt; (const T_CheckPointer&lt;Type&gt; &amp;, const size_t n); </code></pre> <p>to</p> <pre><code>// Specific Template Friendship friend T_CheckPointer&lt;Type&gt; operator+ &lt;&gt; (const T_CheckPointer&lt;Type&gt; &amp;, const size_t n); </code></pre> <p>by deleting the word <strong>type</strong> after the function name, then all will be okay.</p> <p>Anyone can tell me the reason?</p> <hr> <p>For information, there is the <strong>error message</strong> when I call</p> <pre><code>int iarr[] = {1, 2, 3, 4}; T_CheckPointer&lt;int&gt; itcp(iarr, iarr+4); </code></pre> <p>error message:</p> <pre><code>/usr/include/c++/4.4/bits/stl_iterator_base_types.h: In instantiation of ‘std::iterator_traits&lt;int&gt;’: /usr/include/c++/4.4/bits/stl_iterator.h:96: instantiated from ‘std::reverse_iterator&lt;int&gt;’ ../Classes/T_CheckPointer.hpp:31: instantiated from ‘T_CheckPointer&lt;int&gt;’ ../PE16.cpp:520: instantiated from here /usr/include/c++/4.4/bits/stl_iterator_base_types.h:127: error: ‘int’ is not a class, struct, or union type /usr/include/c++/4.4/bits/stl_iterator_base_types.h:128: error: ‘int’ is not a class, struct, or union type /usr/include/c++/4.4/bits/stl_iterator_base_types.h:129: error: ‘int’ is not a class, struct, or union type /usr/include/c++/4.4/bits/stl_iterator_base_types.h:130: error: ‘int’ is not a class, struct, or union type /usr/include/c++/4.4/bits/stl_iterator_base_types.h:131: error: ‘int’ is not a class, struct, or union type </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. USTianyi
    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. POSpecific Template Friendship in C++
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. POSpecific Template Friendship in C++
      1. This table or related slice is empty.
      1. VTUpMod
    3. VO
      singulars
      1. POSpecific Template Friendship in C++
      1. This table or related slice is empty.
      1. VTUpMod
    1. COWhat is the error message?
      singulars
      1. POSpecific Template Friendship in C++
      1. USenobayram
    2. CO@enobayram, thanks for your attention, I have put them in the article.
      singulars
      1. POSpecific Template Friendship in C++
      1. USTianyi
    3. COCould you provide a **minimal** example (that compiles on e.g. Ideone) that displays the problem? And did you try upgrading to gcc 4.7?
      singulars
      1. POSpecific Template Friendship in C++
      1. USTemplateRex
 

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