C++基础语法练习

#include <iostream>
#include <cstdio>
using namespace std;

class A
{
public:
A(){ cout << "A's default constructor called" << endl; }
A(int i) {
a = i;
cout << "A's constructor called" << endl;
}
void print() { cout << a; }
~A() { cout << "A's destructor called" << endl; }
int getData(){ return a; }
private:
int a;
};

class B:public A
{
public:
B(){ cout << "B's default constuctor called" << endl; }
B(int i, int j, int k): A(i), aa(j) {
b = k;
cout << "B's constructor called" << endl;
}
void print();
~B() { cout << "B's destructor called" << endl; }
private:
int b;
A aa;
};
void B::print(){
A::print();
cout << b << aa.getData() << endl;
}

int main() {
B bb[2] = { B(1, 2, 3), B(20, 30, 40) };
for(int i = 0; i < 2; i++)
bb[i].print();
return 0;
}

int &f1(int &a) {
a += a;
return a;
}
int f2(int b) {
b += b;
return b;
}
int main()
{
int x, y, z;
x = 10;
y = f1(x);
z = f2(x);
cout << x << endl;
cout << y << endl;
cout << z << endl;
}
class A
{
private:
int a;
static int b;
public:
A(){}
A(int i) {
a = i;
b += i;
}
void out() {
cout << a << b << endl;
}
};
int A::b = 0;

int main() {
A obj1(10);
obj1.out();
A obj2(15);
obj2.out();
obj1.out();
}

int i = 0, sum = 0;
int main()
{
for(;;){
i += 2;
if(i > 10) break;
else if(i == 8) continue;
sum += i;
}
cout << i << sum <<  endl;
}

int main()
{
int a = 1, b = 2, c = 3;
int d = 4, y = 10;
switch(y)
{
case 1:
a++; break;
default:
d = 1;
case 2:
b++; break;
case 3:
c++; break;
}
cout << a << b << c << d << endl;
}

int main()
{
int i, j, m, n;
i = 2;
j = 4;
m = ++i + j++;
n = (++i) + (++j);
cout << i << j << m << n << endl;
return 0;
}