版权声明:转载请注明出处。作者:两仪织,博客地址:http://blog.csdn.net/u013894427 https://blog.csdn.net/u013894427/article/details/83350205
表现形式有三种
- 当前类进行初始化,尤其是当成员变量是一个const或者一个引用类型
class Demo
{
private:
int b;
public:
Demo(int a):b(a){};
}
- 需要在初始化列表中调用外部类成员的初始化函数
#include <iostream>
using namespace std;
class C1
{
private:
int a;
int b;
int c;
public:
C1(int a,int b,int c)
{
cout << "Class 1 construct function" << endl;
};
};
class C2
{
private:
C1 c1Obj;
public:
C2():c1Obj(1,2,3)//这里用的是类1对象的
{
cout << "Class 2 construct function" << endl;
};
};
int main()
{
C2 c2Obj;
return 1;
}
最后打印的结果是
Class 1 construct function
Class 2 construct function
- 派生类要在初始化列表中调用父类的构造函数
#include <iostream>
using namespace std;
class Base
{
public:
Base(int a) : val(a) {}
private:
int val;
};
class Derived : public Base
{
public:
//多个参数用逗号隔开
Derived(int v) : p(v), Base(v) {}
void print_val() { cout << "hello:" << p << endl;}
private:
int p;
};
int main(int argc ,char **argv)
{
int pp = 45;
Derived b(pp);
b.print_val();
}
打印结果如下
hello:45