Template class friend template function template class friend Template Function

Template Class youyuan template function-Zookeeper second-blog

Template class friend Template Function

 

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# Include <iostream> # Include <string> Using Namespace STD; Template < Class T> Class Test; Template < Class T> ostream & operator <(ostream & out, Const Test <t> & OBJ ); Template < Class T> Class Test { Private : Int Num; Public : Test ( Int N = 0) { Num = N; } Test ( Const Test <t> & copy) { Num = copy. Num; } // '<' Followed by '<>' indicates that this function is a function template. Friend Ostream & operator <> (ostream & out, Const Test <t> & OBJ ); }; Template < Class T> ostream & operator <(ostream & out, Const Test <t> & OBJ) { Cout <obj. Num <Endl; Return Out; }   Int Main () { Test < Int > T (2 ); Cout <t <Endl; Getchar (); Return 0; }

 

1) It should be noted that the template <class T> should appear exactly where and where.

2) It is important to note that the comment row is added,

  1:   friend   ostream  &  operator  <> ( ostream  &  out ,  const   test   T  &  OBJ ); 

This line cannot be written as well,

  1:   friend template   class   T   ostream  &  operator  <> ( ostream  &  out ,  const   test   T  &  OBJ ); 

It cannot be written like this,

  1:   friend template   class   T   ostream  &  operator  <( ostream  &  out ,  const   test   T  &  OBJ ); 

In short, the only correct method isCodeSection. <> It is also essential. In fact, <> there are two meanings: one is, indicating that the friend function is a function template; the other is, the template type parameter used by this template is the type parameter class t of the current template class.

 

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123456789101112131415161718192021222324252627282930313233343536

# Include <iostream> # Include <string> Using Namespace STD; Template < Class T> Class Test; Template < Class T> ostream & operator <(ostream & out, Const Test <t> & OBJ ); Template < Class T> Class Test { Private : Int Num; Public : Test ( Int N = 0) { Num = N; } Test ( Const Test <t> & copy) { Num = copy. Num; } // '<' Followed by '<>' indicates that this function is a function template. Friend Ostream & operator <> (ostream & out, Const Test <t> & OBJ ); }; Template < Class T> ostream & operator <(ostream & out, Const Test <t> & OBJ) { Cout <obj. Num <Endl; Return Out; }   Int Main () { Test < Int > T (2 ); Cout <t <Endl; Getchar (); Return 0; }

 

1) It should be noted that the template <class T> should appear exactly where and where.

2) It is important to note that the comment row is added,

  1:   friend   ostream  &  operator  <> ( ostream  &  out ,  const   test   T  &  OBJ ); 

This line cannot be written as well,

  1:   friend template   class   T   ostream  &  operator  <> ( ostream  &  out ,  const   test   T  &  OBJ ); 

It cannot be written like this,

  1:   friend template   class   T   ostream  &  operator  <( ostream  &  out ,  const   test   T  &  OBJ ); 

In short, the only correct method is in the code segment. <> It is also essential. In fact, <> there are two meanings: one is, indicating that the friend function is a function template; the other is, the template type parameter used by this template is the type parameter class t of the current template class.