1 #include <iostream>
2 #include <
string>
3 using namespace std;
4
5 class Type{
6 public:
7 string Name;
8 };
9
10 class O{
11 public:
12 virtual void ToString(){
13 cout<<
"O" <<
endl;
14 }
15 virtual Type GetType(){
16 Type t;
17 t.Name=
"O";
18 return t;
19 }
20 };
21
22 template<
class T>
23 class V :
public O{
24 public:
25 V<T>
(){
26
27 }
28 public:
29 void ToString(){
30 Type t=
T::ClassType();
31 cout<< t.Name <<
endl;
32 }
33 };
34
35
36
37 class D:
public V<D>
{
38 public:
39 static Type ClassType(){
40 Type t;
41 t.Name=
"D";
42 return t;
43 }
44 public:
45 D() { }
46
47 Type GetType(){
48 Type t;
49 t.Name=
"D";
50 return t;
51 }
52 void ToString(){
53 cout <<
"DDDD" <<
endl;
54 }
55 };
56
57
58
59 int main(){
60 O* o =
new O();
61 o->
ToString();
62
63 D* d =
new D();
64 d->
ToString();
65
66 cin.
get();
67 }
1 //下面的代码 耗时完全相同 —— 指针类型的转换 完全不浪费任何时间
2 cout<<
"AAA"<<
endl;
3 for(
long long i=
0;i<
1024*
1024*
1024;i++)
//每秒3.5Y次左右
4 {
5 //这两种指针转换 性能完全相同
6 //O* t =(O*)d;
7 O* t = static_cast<O*>
(d);
8 }
9 cout<<
"BBB"<<
endl;
10 for(
long long i=
0;i<
1024*
1024*
1024;i++
)
11 {
12 }
13 cout<<
"CCC"<<endl;
转载于:https://www.cnblogs.com/redc/p/Temp_2018_12_06.html
