类学习之一Pass arguments to base class

#include <iostream>using namespace std;class BaseClass {  int i;public:  BaseClass(int n) {     cout << "Constructing base class\n";     i = n;  }  ~BaseClass() {     cout << "Destructing base class\n";   }  void showi() {     cout << i << '\n';   }};class DerivedClass : public BaseClass {  int j;public:  DerivedClass(int n, int m) : BaseClass(m) {     cout << "Constructing DerivedClass class\n";     j = n;  } 

<pre name="code" class="cpp">//DerivedClass(int n, int m) : BaseClass(m),j(n) { //    cout << "Constructing DerivedClass class\n"; //  }

~DerivedClass() { cout << "Destructing DerivedClass class\n"; } void showj() { cout << j << '\n'; }};int main(){ DerivedClass o(10, 20); o.showi(); o.showj(); return 0;}