Common usage of C ++ templates

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C ++Programming LanguageTo a certain extent, the template application inProgramDevelopment efficiency. Here we areArticleI want to explain in detail the basic concepts of C ++ templates. I hope that beginners can fully master this knowledge through the content introduced in this article.

Some time ago, I re-learned C ++, mainly focusing on C ++ programming ideas and C ++ new design ideas. I have a better understanding of the use of the template, which is summarized as follows:

Common C ++ templates are listed below:

1. Static members of the c ++ template class

2. Template<TypenameT>Struct testclass
4. {
6. Static int _ data;
8. };
10. Template<>Int testclass<Char>: _ DATA=1;
12. Template<>Int testclass<Long>: _ DATA=2;
14. Int main (void ){
16. Cout< Boolalpha <(1= Testclass<Char>: _ Data)< Endl;
18. Cout< Boolalpha <(2= Testclass<Long>: _ Data)< Endl;
20. }

2. The C ++ template class is special.

2. Template<ClassI, Class O>Struct testclass
4. {
6. Testclass () {cout<"I, O"< Endl;}
8. };
10. Template<ClassT>Struct testclass<T*, T *>
12. {
14. Testclass () {cout<"T *, T *"< Endl;}
16. };
18. Template<ClassT>Struct testclass<ConstT *, T *>
20. {
22. Testclass () {cout<"Const T *, T *"< Endl;}
24. };
26. Int main (void)
28. {
30. Testclass<Int, Char>Obj1;
32. Testclass<Int*, Int *>Obj2;
34. Testclass<ConstInt *, int *>Obj3;
36. }

3. Class templates + function templates

2. Template<ClassT>Struct testclass
4. {
6. Void swap (testclass<T>&) {Cout<"Swap ()"< Endl;}
8. };
10. Template<ClassT>Inline void swap (testclass<T>& X,
    Testclass<T>& Y)
12. {
14. X. Swap (y );
16. }
18. Int main (void)
20. {
22. Testclass<Int>Obj1;
24. Testclass<Int>Obj2;
26. Swap (obj1, obj2 );
28. }

4. class member function Template

2. Struct testclass
4. {
6. Template< ClassT>Void mfun (const T & T)
8. {
10. Cout< <T < <Endl;
12. }
14. Template< ClassT>Operator T ()
16. {
18. Return T ();
20. }
22. };
24. Int main (void)
26. {
28. Testclass OBJ;
30. OBJ. mfun (1 );
32. IntI=OBJ;
34. Cout< <I < <Endl;
36. }

5. Derivation of default C ++ template parameters

2. Template< ClassT>Struct Test
4. {
6. T;
8. };
10. Template< ClassI, ClassO=Test< I> >Struct testclass
12. {
14. I B;
16. O C;
18. };
20. Void main ()
22. {
24. }

6. Non-type C ++ template parameters

2. Template< ClassT, int n>Struct testclass {
4. T _ t;
6. Testclass (): _ T (n ){
8. }
10. };
12. Int main (void ){
14. Testclass< Int, 1>Obj1;
16. Testclass< Int, 2>Obj2;
18. }

7. Empty template parameters

2. Template< ClassT>Struct testclass;
4. Template< ClassT>BoolOperator= (Const testclass< T>&,
   Const testclass< T>&)
6. {
8. Return false;
10. };
12. Template< ClassT>Struct testclass
14. {
16. Friend boolOperator=< >
    (Const testclass &, const testclass &);
18. };
20. Void main ()
22. {
24. }

8. template class

2. Struct widget1
4. {
6. Template< TypenameT>
8. T Foo (){}
10. };
12. Template< Template< ClassT>Class X>
14. Struct widget2
16. {
18. };
20. Void main ()
22. {
24. Cout< <3 < <'\ N ';
26. }

The above is an introduction to some common methods of the C ++ template.