typeid, const_cast<Type>的使用

 1 #include <bits/stdc++.h>
 2 using namespace std;
 3 
 4 class A {
 5     public :
 6         void Show() {
 7             cout << "A" << endl;
 8         }
 9 } ;
10 
11 class CC {
12     public :
13         void Show() {
14             cout << "CC" << endl;
15         }
16 } ;
17 
18 class x {
19     public :
20         void Show() {
21             cout << "x" << endl;
22         }
23 } ;
24 
25 class {
26 } test;
27 
28 int main() {
29     long long a, *b = 0;
30     int *c;
31     double *d;
32     cout << (typeid(a) == typeid(long long)) << endl;
33     cout << (typeid(a) == typeid(double)) << endl;
34     b = &a;
35     cout << (typeid(*b) == typeid(long long)) << endl;
36     cout << typeid(b).name() << endl;
37     cout << typeid(*b).name() << endl;
38     cout << typeid(c).name() << endl;
39     cout << typeid(*c).name() << endl;
40     cout << typeid(d).name() << endl;
41     cout << typeid(*d).name() << endl;
42     A t;
43     cout << typeid(t).name() << endl;
44     CC s;
45     cout << typeid(s).name() << endl;
46     x *p;
47     cout << typeid(p).name() << ' ' << typeid(*p).name() << endl;
48     class {
49     } temp;
50     cout << typeid(temp).name() << endl;
51     cout << typeid(test).name() << endl;
52     class {
53     } temp2;
54     cout << typeid(temp2).name() << endl;
55     class a {
56     } temp3;
57     cout << typeid(temp3).name() << endl;
58     cout << typeid(long).name() << endl;
59     unsigned long long l;
60     cout << typeid(l).name() << endl;
61     short z;
62     cout << typeid(z).name() << endl;
63     return 0;
64 }

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运行结果：

 1 1
 2 0
 3 1
 4 Px
 5 x
 6 Pi
 7 i
 8 Pd
 9 d
10 1A
11 2CC
12 P1x 1x
13 Z4mainEUt_
14 5._125
15 Z4mainEUt0_
16 Z4mainE1a
17 l
18 y
19 s
20 
21 
22 // 在ubuntu 13.10下的运行结果

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const_cast<Type>去除const或volatile限制：

 1 #include <bits/stdc++.h>
 2 using namespace std;
 3 
 4 char *Test(const char *s) {
 5     char *t = const_cast<char *>(s);
 6     *t = 'z';
 7     return t;
 8 }
 9 
10 int main() {
11     const char *s1 = "abc";
12     const char s2[] = "cba";
13     //cout << Test(s1) << endl; // Run-Time Error
14     cout << Test(s2) << endl;
15     cout << s2 << endl;
16     //cout << Test("ABC") << endl; // Run-Time Error
17     return 0;
18 }

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 1 #include <bits/stdc++.h>
 2 using namespace std;
 3 
 4 void change(const int *pt) {
 5     int *pc = const_cast<int *> (pt);
 6     *pc = 100;
 7 }
 8 
 9 int main() {
10     int pop1 = 18181;
11     const int pop2 = 2000;
12     cout << pop1 << ' ' << pop2 << endl;
13     change(&pop1);
14     change(&pop2);
15     cout << pop1 << ' ' << pop2 << endl;
16     return 0;
17 }

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——written by Lyon