C++11中提供的繼承構(gòu)造函數(shù)可以讓派生類直接使用基類的構(gòu)造函數(shù)，而無(wú)需自己再寫(xiě)構(gòu)造函數(shù)，尤其是在基類有很多構(gòu)造函數(shù)的情況下，可以極大地簡(jiǎn)化派生類構(gòu)造函數(shù)的編寫(xiě)。

先來(lái)看沒(méi)有繼承構(gòu)造函數(shù)之前的處理方式:
代碼如下:

#include <iostream> #include <string> using namespace std;class Base { public:Base(int i):m_i(i){}Base(int i,double j):m_i(i),m_j(j){}Base(int i,double j,string k):m_i(i),m_j(j),m_k(k){}int m_i;double m_j;string m_k; };class Child :public Base { public:Child(int i):Base(i){}Child(int i,double j):Base(i,j){}Child(int i,double j,string k):Base(i,j,k){}};int main() {Child c(520, 13.14, "I Love You");cout << "int = " << c.m_i << " double = " << c.m_j << " string = " << c.m_k << endl;return 0; }

測(cè)試結(jié)果:

繼承構(gòu)造函數(shù)
代碼如下:

#include <iostream> #include <string> using namespace std;class Base { public:Base(int i):m_i(i){}Base(int i,double j):m_i(i),m_j(j){}Base(int i,double j,string k):m_i(i),m_j(j),m_k(k){}int m_i;double m_j;string m_k; };class Child :public Base { public:using Base::Base;};int main() {Child c(520, 13.14, "I Love You");cout << "int = " << c.m_i << " double = " << c.m_j << " string = " << c.m_k << endl;return 0; }

測(cè)試結(jié)果:

如果子類中有跟父類一樣的同名函數(shù)，就會(huì)隱藏父類的一樣同名的函數(shù)。

代碼如下:

#include <iostream> #include <string> using namespace std;class Base { public:Base(){}Base(int i):m_i(i){}Base(int i,double j):m_i(i),m_j(j){}Base(int i,double j,string k):m_i(i),m_j(j),m_k(k){}void func(int i){cout << "base func(int i)" << endl;}void func(int i, string str){cout << "base func(int i,string str)" << endl;}int m_i;double m_j;string m_k; };class Child :public Base { public:using Base::Base;void func(){cout << "child func()" << endl;}};int main() {Child c;c.func();//c.func(2);//error//c.func(2, "Tom");//errorreturn 0; }

測(cè)試結(jié)果:

在子類中加入下面這條代碼，則可以解除隱藏。

using Base::func;

代碼如下:

#include <iostream> #include <string> using namespace std;class Base { public:Base(){}Base(int i):m_i(i){}Base(int i,double j):m_i(i),m_j(j){}Base(int i,double j,string k):m_i(i),m_j(j),m_k(k){}void func(int i){cout << "base func(int i)" << endl;}void func(int i, string str){cout << "base func(int i,string str)" << endl;}int m_i;double m_j;string m_k; };class Child :public Base { public:using Base::Base;using Base::func;void func(){cout << "child func()" << endl;}};int main() {Child c;c.func();c.func(2);c.func(2, "Tom");return 0; }

測(cè)試結(jié)果:

總結(jié)

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