在构造函数中初始化成员变量

Question

此行代码在stack.cpp文件中出现错误：

array=[data,data,data]
const concurrency=3
from(array).pipe(mergeMap(request=>this.http
    .post(this.url + this.saveRequestUrl, request, this.options),null,concurrency)

该错误表明变量stack::stack() 未初始化。始终初始化成员变量（类型6）。有人可以帮我理解这里的问题吗？我需要在cpp文件或头文件中解决该问题吗？应用程序是将元素压入和弹出堆栈。

stack::el

这是我的stack.h头文件

#include <iostream>
#include "Stack.h"
using namespace std;

stack::stack() //stack class constructor
{
    top = -1; // start out with an empty stack represented by -1 
}

stack::~stack()  //destructor
{

}

bool stack::isEmpty() { //Function to determine if the stack is empty
    if (top == -1) { 
        return true; 
    } else {
        return false;
    }
}

bool stack::isFull() { // Function to determine if the stack is full
    if (top == MAX - 1) {
        return true;
    }   else {
        return false;
    }
}

void stack::push(el_t elem) { //Function to push an element onto the top of the stack
    if (isFull()) {
        // lookup exception handling document
    }
    else {
        top++; el[top] = elem;
        cout << elem << " pushed onto the stack" << endl;
    }
}

void stack::pop(el_t& elem) { //Function to pop the top element from the stack, using pass by reference
    if (isEmpty()) {
        //underflow exception handling
    } else {elem = el[top]; top--;}
}

void stack::displayAll() //Function to display all elements in the stack
{
    if (isEmpty()) {
        cout << "Stack is empty" << endl;
    }
    else {
        for (int i = top; i >= 0; i--)
            cout << el[i] << endl;
    }
}

void stack::topElem(el_t& elem) //Function to get the top element of a stack
{
    if (isEmpty()) {
        //underflow exception handling
    }
    else {
        elem = el[top];
    }
}

void stack::clearIt()
{
    el_t temp = 'a';
    cout << "Clearing the stack..." << endl;
    while (!isEmpty()) {
        pop(temp);
    }
}