错误：请求成员'..'在'this'，这是非类类型' - * const' [英] error: request for member '..' in 'this', which is of non-class type '--* const'

问题描述

我的第一个问题在这里。请原谅我，我刚刚进入C ++，并开始与DS。 STACK !!!

我的代码：我认为

  std; 
 typedef char stackElement; 
 
类栈
 {
 public：
 stackElement * contents; //动态分配：因为我们不知道什么是我们的数组的大小。 
 int top，maxSize; // current数组中的最高索引
 
 //数组的最大尺寸;我们需要它知道数组是否已满
 
 stack（int maxSize）
 {
 
 contents = new stackElement（maxSize）; 
 this.maxSize = maxSize; 
 if（contents == NULL）
 {
 cout<<Insufficient memory; 
 exit（1）; 
 
} 
 
 top = -1; 
} 
〜Stack（）
 {
 delete [] content; 
 contents = NULL; 
 maxSize = 0; 
 top = -1; 
 
} 
 
 bool isEmpty（）const 
 {
 
 return top< 0; 
} 
 bool isFull（）const 
 {
 
 return top == maxSize  -  1; 
} 
 
 
 void push（stackElement element）
 {
 if（isFull（））
 {
 cout< ;STACK IS ALREADY FULL; 
 exit（1）; 
} 
 top = top + 1; 
 contents [top] = element; 
} 
 
 
}; 
 
 int main（）
 {
 
 cout<<STACK IMPLEMENTATION; 
 int i = 1; 
 stack s1（i）; 
 
 
 s1.push（'a'）; 
 s1.push（'1'）; 
 return 0; 
} 
  

我收到此错误：

 错误：请求'this'中的成员'maxSize'，它是非类型'Stack * const'
  

解决方案

如果有，你必须写 this-> maxSize = maxSize; ，因为此是一个指针。

但是最好不要写这个，而是使用构造函数初始化列表：

 显式Stack（int m）
：contents（new stackElement [m]），top（-1），maxSize（m）
 {
 //没有别的事情
} 
  

我还添加了 explicit ，所以你不会意外转换 5 into a Stack 。

/ p>

此外，您不需要检查 contents 不为null：当 new 失败，退出时出现异常，它不会返回空指针。

这是至关重要的，注意，你至多有一个赤裸裸的 new - 在您的构造函数中。其他任何事情都是一个例外 - 安全灾难，您需要重构和使用单一责任资源管理类。

---

析构函数应该是：〜Stack（）{delete [] content; }

---

想象一下，你必须支付

strong>为你写的每一行代码。耐心，失去源头，思考。

My first ever question here. Please excuse me, I have just entered into C++ and was starting up with DS. STACK!!!

My code: I think

    using namespace std;
    typedef char stackElement;

    class Stack
    {
    public:
        stackElement *contents;   //dynamically allocated: as we do not know what would be the size of our array.
        int top, maxSize;               // current Top index in the array

                //max size of the array; we need it to know if the array is full

    Stack(int maxSize)
    {

        contents = new stackElement(maxSize);
        this.maxSize = maxSize;
        if(contents == NULL)
        {
            cout<<"Insufficient memory";
            exit(1);

        }

        top = -1;
    }
    ~Stack()
    {
        delete [] contents;
        contents = NULL;
        maxSize = 0;
        top = -1;

    }

    bool isEmpty()const
    {

        return top < 0;
    }
    bool isFull() const
    {

        return top == maxSize - 1;
    }


    void push(stackElement element)
    {
        if(isFull())
        {
            cout<<"STACK IS ALREADY FULL";
            exit(1);
        }
        top = top + 1;
        contents[top] = element;
    }


};

int main()
{

    cout<<"STACK IMPLEMENTATION";
    int i = 1;
    Stack s1(i);


    s1.push('a');
    s1.push('1');
    return 0;
}

I am getting this error:

error: request for member 'maxSize' in 'this', which is of non-class type 'Stack* const'

解决方案

If at all, you'd have to write this->maxSize = maxSize;, since this is a pointer.

But better not to write that at all and instead use the constructor-initializer list:

  explicit Stack(int m)
  : contents(new stackElement[m]), top(-1), maxSize(m)
  {
      // nothing else to do
  }

I also added explicit so you don't accidentally convert 5 into a Stack.

You also wrote the array initialization wrong.

Also, you don't need to check that contents is not null: When new fails, it exits with an exception, it does not return a null pointer. (That behaviour would make no sense when you think in terms of objects.)

It is crucial to note that you have at most one naked new-expression in your constructor. Anything else is an exception-safety disaster, and a sign that you need to refactor and use single-responsibility resource-managing classes.

---

The destructor should just be: ~Stack() { delete [] contents; } Everything else is pointless waste.

---

Imagine you had to pay for every line of code you write. Be patient, lose the source, think.

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