与构造函数/析构函数定义相关的 c++ 编译错误

c++ compiling error related to constructor/destructor definition

提问by Michael Burr

I'm trying to define the constructor and destructor of my class but I keep getting the error:

我正在尝试定义我的类的构造函数和析构函数，但我不断收到错误消息：

definition of implicitly-declared 'x::x()'

隐式声明的 'x::x()' 的定义

What does it mean?

这是什么意思？

Part of the code:

部分代码：

///Constructor
StackInt::StackInt(){
    t = (-1);
    stackArray = new int[20];
};

///Destructor
StackInt::~StackInt(){
    delete[] stackArray;
}

回答by Michael Burr

In the class declaration (probably in a header file) you need to have something that looks like:

在类声明中（可能在头文件中），您需要具有如下所示的内容：

class StackInt {
public:
    StackInt();
    ~StackInt();  
}

To let the compiler know you don't want the default compiler-generated versions (since you're providing them).

让编译器知道您不想要默认的编译器生成的版本（因为您提供了它们）。

There will probably be more to the declaration than that, but you'll need at least those - and this will get you started.

声明中可能会有更多内容，但您至少需要这些 - 这将使您开始。

You can see this by using the very simple:

您可以通过使用非常简单的方式看到这一点：

class X {
        public: X();   // <- remove this.
};
X::X() {};
int main (void) { X x ; return 0; }

Compile that and it works. Then remove the line with the comment marker and compile again. You'll see your problems appear then:

编译它，它的工作原理。然后删除带有注释标记的行并再次编译。然后你会看到你的问题出现：

class X {};
X::X() {};
int main (void) { X x ; return 0; }

qq.cpp:2: error: definition of implicitly-declared `X::X()'

回答by taronish4

Another thing to keep in mind is that everything that the constructor accesses must be public. I have gotten this error before.

要记住的另一件事是构造函数访问的所有内容都必须是公共的。我以前遇到过这个错误。

class X{
   T *data;
 public:      // <-move this to include T *
   X();
   ~X();
}

This code still have the error because in my constructor I had the following:

这段代码仍然有错误，因为在我的构造函数中，我有以下内容：

X::X(){data = new T();

Which meant that although I had made the constructor and destructor public, the data they were working with was still private, and I still got the "definition of implicitly-declared" error.

这意味着虽然我已经公开了构造函数和析构函数，但它们使用的数据仍然是私有的，我仍然收到“隐式声明的定义”错误。