Answer & Explanation 答案与解释

Correct Answer: 3

正确答案：3

Both default and copy constructors

默认构造函数和复制构造函数

In C++ class implementation, if we do not create any constructor, the default and copy constructors are added automatically to the class.

在C ++类实现中，如果我们不创建任何构造函数，则默认构造函数和复制构造函数会自动添加到该类中。

Answer & Explanation 答案与解释

Correct Answer - 2

正确答案-2

Yes

是

If we do not implement the assignment operator, it automatically added to the class.

如果我们不实现赋值运算符，它将自动添加到类中。

#include<iostream>
using namespace std;
//class definition
class Example {
Example() { 
cout << "Constructor called"; 
}
};
//main() code 
int main()
{
Example Ex;
return 0;
}

Answer & Explanation 答案与解释

Correct Answer - 3

正确答案-3

Compile time error

编译时间错误

In the class definition, there is no access modifier is specified, thus (as per the standard) all member functions and data members are private by default. And, the constructor cannot be a private.

在类定义中，没有指定访问修饰符，因此(按照标准)所有成员函数和数据成员默认情况下都是私有的。 并且，构造函数不能为私有。

This will be the output

这将是输出

main.cpp:6:5: error: 'Example::Example()' is private
Example() {

#include <iostream>
using namespace std;
//class definition
class Example {
public:
Example()
{
cout << "Constructor called ";
}
};
//main() code
int main()
{
Example Ex1, Ex2;
return 0;
}

Answer & Explanation 答案与解释

Correct Answer - 2

正确答案-2

Constructor called Constructor called

构造函数称为构造函数称为

In the class definition, the constructor is public, so there is no any compile time or run time error. We are creating two objects “Ex1” and “Ex2” of “Example” class; constructor will be called two times. Thus, the output will be "Constructor called Constructor called".

在类定义中，构造函数是公共的，因此没有任何编译时或运行时错误。 我们正在创建“ Example”类的两个对象“ Ex1”和“ Ex2”； 构造函数将被调用两次。 因此，输出将为“称为构造函数的构造函数，称为” 。

#include <iostream>
using namespace std;
//class definition
class Example {
public:
int a;
int b;
};
//main() code
int main()
{
Example Ex1 = { 10, 20 };
cout << "a = " << Ex1.a << ", b = " << Ex1.b;
return 0;
}

Answer & Explanation 答案与解释

Correct Answer - 3

正确答案-3

a = 10, b = 20

a = 10，b = 20

Like structures, we can initialize class's public data members (using initializer list) like this Example Ex1 = {10, 20}; so, 10 will be assigned to a and 20 will be assigned to b. Thus, the output will be a = 10, b = 20.

像结构一样，我们可以像下面的示例一样初始化类的公共数据成员(使用初始化器列表) Ex1 = {10，20}; 因此，将10分配给a ，将20分配给b 。 因此，输出将为a = 10，b = 20 。