C++基礎（一）
阿新 • • 發佈：2018-04-03
C++基礎# include <iostream>
# include <stdio.h>
class A {
public:
A() :i(10) { }
virtual void f() {
std::cout << "A::f() i = " << i << std::endl;
}
int i;
};
class B : public A
{
public:
B() :j(20) { }
virtual void f() { std::cout << "B::f() j = " << j<< std::endl; }
int j;
};
int main()
{
A *a = new A();
std::cout << "A *a = new A(); " << std::endl;
std::cout << "a->i = " << a->i << std::endl;
A b;
std::cout << "A b; " << std::endl;
std::cout << "A c; " << std::endl;
A c;
std::cout << "b.i = " << b.i << std::endl << std::endl;;
int* p = (int*)&b;
int* p2 = (int*)&a;
int* p3 = (int*)&c;
int* p4 = (int*)*p;
std::cout << "int* p4 = (int*)*p; the *p4 is " << *p4 << std::endl;
std::cout << "int* p4 = (int*)*p; the p4 is " << p4 << std::endl;
std::cout << "int* p3 = (int*)&c; the *p3 is " << *p3 << std::endl;
std::cout << "int* p = (int*)&b; the *p is " << *p << std::endl;
std::cout << "*p2 = " << *p2 << std::endl;
std::cout << "a is a point : A* a = new A(); the sizeof(a) is " << sizeof(a) << std::endl;
std::cout << "b is a object : A b; the sizeof(b) is " << sizeof(b) << std::endl<<std::endl;
p++;
p2++;
std::cout << "*(p++) = " << *p << std::endl;
std::cout << "p++ = " << p << std::endl;
std::cout << "*(p2++) = " << *p2 << std::endl;
std::cout << "p2++ = " << p2 << std::endl;
/***********************************************************/
A d;
B e;
A* pa = &e;
pa->f();
char cc = getchar();
return 0;
}
代碼運行結果：
C++基礎（一）