//继承时有关构造函数要注意的一些问题

#include <iostream> using std::cout; using std::endl;

class Base

{     public:         Base(){}         Base(int n){}            };

class C_A1: public Base

{     public:         C_A1(){}         C_A1(int n0,int n1):Base(n0){} };

class C_A0: public Base

{     public:         C_A0(){}         C_A0(int n0,int n1):Base(n0){} };

class C_B0: public C_A0,public C_A1 

{     public:         C_B0(){}; //若定义了此默认构造函数，则它的基类要定义默认构造函数,若未定义

                     //此默认构造函数，则它的基类默认构造函数可有可无         C_B0(int n,int n0,int n1,int n2):C_A0(n,n1),C_A1(n0,n2)         {                   } };

int main()

{       return 0; }

若将上述代码中的C_B0(){}除去，编译时将出现如下的错误

testcpp.cpp: In constructor 'C_B0::C_B0()':

testcpp.cpp:201:15: error: no matching function for call to 'C_A0::C_A0()'

testcpp.cpp:201:15: note: candidates are:

testcpp.cpp:195:9: note: C_A0::C_A0(int, int)

testcpp.cpp:195:9: note:   candidate expects 2 arguments, 0 provided

testcpp.cpp:191:7: note: C_A0::C_A0(const C_A0&)

testcpp.cpp:191:7: note:   candidate expects 1 argument, 0 provided

编译失败。