destructors can not be overloaded
时间: 2024-06-04 10:11:39 浏览: 90
As an AI language model, I can say that destructors in C++ cannot be overloaded because they do not take any arguments and have a fixed name, which is the tilde (~) followed by the class name. This means that there can only be one destructor per class, and it will be automatically called when an object is destroyed. Overloading the destructor would not make sense since it is called automatically and does not need to be called explicitly with different arguments.
相关问题
Destructors can not be overloaded.
As an AI language model, I can tell you that the statement is not entirely true. Destructors can be overloaded in C++, but they cannot be overloaded with parameters. A class can have multiple destructors with different access levels and modifiers, but all of them must have the same name and no parameters. The compiler automatically calls the appropriate destructor based on the type of the object being destroyed.
Write a program illustrating that member object destructors are called for only those member objects that were constructed before an exception occurred. 定义类Item,并包含整型成员变量value,并在Item的构造函数中定义条件判断语句以抛出异常,例如: if ( value == 3 ) throw runtime_error( "An exception was thrown" ); main函数中构建若干Item对象,并在合适位置打印测试语句。
根据C++的异常处理机制,当在一个对象的构造函数中抛出异常时,该对象的析构函数不会被调用,因为该对象并没有完全构造成功。如果一个对象的构造函数中抛出了异常,那么该对象会被释放,而已经构造成功的成员对象会被析构。
下面是一个示例程序,演示了成员对象析构函数的调用情况。程序定义了一个Item类,它包含一个整型成员变量value。在Item的构造函数中,程序会对value进行条件判断,如果value等于3,则抛出一个runtime_error异常。在main函数中,程序构建了多个Item对象,并在合适的位置打印测试语句。程序执行过程中,如果某个Item对象的构造函数抛出了异常,则该对象会被释放,而已经构造成功的成员对象会被析构。
```c++
#include <iostream>
#include <stdexcept>
using namespace std;
class Item
{
public:
Item(int v) : value(v)
{
cout << "Constructing Item " << value << endl;
if (value == 3)
throw runtime_error("An exception was thrown");
}
~Item()
{
cout << "Destructing Item " << value << endl;
}
private:
int value;
};
int main()
{
try
{
Item item1(1);
Item item2(2);
Item item3(3);
Item item4(4);
}
catch (const exception& e)
{
cerr << "Exception caught: " << e.what() << endl;
}
return 0;
}
```
运行上述程序,可以看到程序先输出了构造Item对象的信息,然后在第三个对象的构造函数中抛出了异常。由于该对象没有构造成功,因此它的析构函数也没有被调用。而已经构造成功的对象的析构函数会被调用,依次输出析构Item对象的信息。最终输出异常信息,程序终止。
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