学习C++拷贝构造函数时遇到的疑惑

Question

代码如下:
#include
using namespace std;

class Clock
{
public:
Clock(int newH,int newM,int newS);
Clock();
Clock(Clock &pClk);
void SetTime(int newH=0,int newM=0,int newS=0);
void ShowTime();

private:
    int hour;
    int min;
    int sec;

};

Clock::Clock(int newH,int newM,int newS)
{
hour = newH;
min = newM;
sec = newS;
}

Clock::Clock()
{
hour = 0;
min = 0;
sec = 0;
}

Clock::Clock(Clock &pClk)
{
hour = pClk.hour;
min = pClk.min;
sec = pClk.sec;
}

void Clock::SetTime(int newH, int newM, int newS)
{
hour = newH;
min = newM;
sec = newS;
}

void Clock::ShowTime()
{
cout << "now the time is :\n" << hour << ":" << min << ":" << sec << endl;
}

Clock func()
{
Clock clk(11,30,0);
return clk;
}

int main(void)
{
Clock clk1(10,30,0);
clk1.ShowTime();

cout << "----拷贝构造函数测试----" << endl;
Clock clk2 = func();//该语句编译不通过
//Clock clk2;
//clk2 = func();
clk2.ShowTime();

return 0;

}

用Clock clk2;clk2 = func();没问题,但合并为Clock clk2 = func();就编译不通过,在这里把类Clock简单理解为某个数据类型如int怎么行不通呢?望有大神解惑!

Answer 1

copy构造是 const Clock &

Clock clk2 = func();//这是构造clk2对象

Clock clk2;
clk2= func();//这是调用了operator=，默认的operator=是按位拷贝