typeid, const_cast<Type>的使用

#include <bits/stdc++.h>
using namespace std;

class A {
    public :
        void Show() {
            cout << "A" << endl;
        }
} ;

class CC {
    public :
        void Show() {
            cout << "CC" << endl;
        }
} ;

class x {
    public :
        void Show() {
            cout << "x" << endl;
        }
} ;

class {
} test;

int main() {
    long long a, *b = 0;
    int *c;
    double *d;
    cout << (typeid(a) == typeid(long long)) << endl;
    cout << (typeid(a) == typeid(double)) << endl;
    b = &a;
    cout << (typeid(*b) == typeid(long long)) << endl;
    cout << typeid(b).name() << endl;
    cout << typeid(*b).name() << endl;
    cout << typeid(c).name() << endl;
    cout << typeid(*c).name() << endl;
    cout << typeid(d).name() << endl;
    cout << typeid(*d).name() << endl;
    A t;
    cout << typeid(t).name() << endl;
    CC s;
    cout << typeid(s).name() << endl;
    x *p;
    cout << typeid(p).name() << ' ' << typeid(*p).name() << endl;
    class {
    } temp;
    cout << typeid(temp).name() << endl;
    cout << typeid(test).name() << endl;
    class {
    } temp2;
    cout << typeid(temp2).name() << endl;
    class a {
    } temp3;
    cout << typeid(temp3).name() << endl;
    cout << typeid(long).name() << endl;
    unsigned long long l;
    cout << typeid(l).name() << endl;
    short z;
    cout << typeid(z).name() << endl;
    return 0;
}

运行结果：

1
0
1
Px
x
Pi
i
Pd
d
1A
2CC
P1x 1x
Z4mainEUt_
5._125
Z4mainEUt0_
Z4mainE1a
l
y
s


// 在ubuntu 13.10下的运行结果

const_cast<Type>去除const或volatile限制：

#include <bits/stdc++.h>
using namespace std;

char *Test(const char *s) {
    char *t = const_cast<char *>(s);
    *t = 'z';
    return t;
}

int main() {
    const char *s1 = "abc";
    const char s2[] = "cba";
    //cout << Test(s1) << endl; // Run-Time Error
    cout << Test(s2) << endl;
    cout << s2 << endl;
    //cout << Test("ABC") << endl; // Run-Time Error
    return 0;
}

#include <bits/stdc++.h>
using namespace std;

void change(const int *pt) {
    int *pc = const_cast<int *> (pt);
    *pc = 100;
}

int main() {
    int pop1 = 18181;
    const int pop2 = 2000;
    cout << pop1 << ' ' << pop2 << endl;
    change(&pop1);
    change(&pop2);
    cout << pop1 << ' ' << pop2 << endl;
    return 0;
}

——written by Lyon