当类具有另一个类的数组时，C++ 复制构造函数

Question

我仍在学习类、复制构造函数和重载运算符，所以任何建议/帮助/->都非常感谢!!!

我正在尝试使用类 Test2 创建一个复制构造函数，该类具有来自另一个类 Test1 的私有(private)成员变量。我在代码中注释了给我业务的复制构造函数所在的位置。

这是我在编译时遇到的错误:

assOp.cpp: In copy constructor 'Test2::Test2(const Test2&)':
assOp.cpp:102:25: error: passing 'const Test2' as 'this' argument of 'int Test2:
:getNum()' discards qualifiers [-fpermissive]
  setNum(original.getNum());
                         ^
assOp.cpp:103:27: error: passing 'const Test2' as 'this' argument of 'char* Test
2::getChar()' discards qualifiers [-fpermissive]
  setChar(original.getChar());

代码如下:

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

class Test1
{
    public:
        Test1();
        Test1(const Test1& original);
        int getNum();
        char *getChar();

        void setNum(int x);
        void setChar(char y[]);


    private:
        int num;
        char *ch;

};

class Test2
{
    public:
        Test2();
        Test2(const Test2& original);

        void setNum(int x);
        void setChar(char y[]);

        int getNum();
        char *getChar();

    private:
        Test1  foo;


};

int main()
{

    Test1 a;
    Test2 b;



    return 0;
}

Test1::Test1()
{
    num = 1234;
    ch = new char[5];
    strcpy(ch,"test");
}

Test1::Test1(const Test1& original)
{
    int length = strlen(original.ch); 

    num = original.num;
    ch = new char[length + 1];
    strcpy(ch, original.ch);
    ch[length] = '\0';

}

int Test1::getNum()
{
    return num;
}

char *Test1::getChar()
{
    return ch;
}

void Test1::setNum(int x)
{
    num = x;
}

void Test1::setChar(char y[])
{
    int length = strlen(y); 
    ch = new char[length + 1];
    strcpy(ch, y);
    ch[length] = '\0';

}

Test2::Test2()
{

}

//Sassy copy constructor that thinks its better than me
Test2::Test2(const Test2& original)
{

    setNum(original.getNum());
    setChar(original.getChar());


}

void Test2::setNum(int x)
{
    foo.setNum(x);
}

void Test2::setChar(char y[])
{
    foo.setChar(y);

}

int Test2::getNum()
{
    return foo.getNum();
}

char *Test2::getChar()
{
    return foo.getChar();
}
                       ^

Answer 1

问题是由

引起的

    int getNum();
    char *getChar();

因为这些函数不是const 成员函数，所以它们不能用在const 对象上。作为一般规则，将所有 getter 函数设为 const 成员函数。

    int getNum() const;
    char const* getChar() const;