在C ++中使用队列和堆栈对2个向量进行加减运算

Question

I have a problem with my C++ code. I need to add and substract 2 math vectors component by component using some header files but I can also implement some other functions. The thing is that my program doesn't have any errors but it's not executing... For example, if I have vector A(3,5) and B(1,7) the results should be: A+B=(4,12) and AB=(2, -2). This is my main .cpp file:

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

template<typename T>
class App {
    public:
        Stack<T> stack;
        T minEle;
        App(Stack<T> stack) {
            this->stack = stack;
        }
        T sum(){
            Stack<T> tempStack = stack;
            T sum=1;
            for(int i=0;i<stack.getTopLevel();i++){

            sum+=tempStack.peek();
            tempStack.pop();
        }
            return sum;
        }
        T substract(){
            Stack<T> tempStack = stack;
            T sum=1;
            for(int i=0;i<stack.getTopLevel();i++){

            sum-=tempStack.peek();
            tempStack.pop();
        }
            return sum;
        }
};

int main(){
  Stack<int> myStack;
    App<int> a(myStack);
    int values[7] = {5, 2, 3, 1, 4, 8, 6};
    int values1[7] = {5, 2, 3, 1, 4, 8, 6};
    for(int i=0;i<8;i++)
    myStack.push(values[i]);
    myStack.push(values1[i]);
    cout<<a.sum();
  return 0;
}

Also, here you can find the queque.h file: https://pastebin.com/yg0CdCnd and the stack_base: https://pastebin.com/P6rzQJC1 Thanks, any help would be useful!

Answer 1

You need to add parantheses to your main function otherwise it won't run.

int main()
{
  Stack<int> myStack;
  App<int> a(myStack);
  int values[7] = {5, 2, 3, 1, 4, 8, 6};
  int values1[7] = {5, 2, 3, 1, 4, 8, 6};
  for(int i=0;i<8;i++)
  myStack.push(values[i]);
  myStack.push(values1[i]);
  cout<<a.sum();
  return 0;
}

I have not checked if your code is correct, but that's the reason why it will not execute.

Answer 2

Your implementation of sum() and subtract() is flawed. You shouldn't refer to getTopLevel at all. It is defined in the linked header file as being the index of the top item of the stack in the internal array. This is an implementation detail of Stack and shouldn't really be part of the public interface.

Instead I suggest you use Stack as it is intended - by pushing elements onto it and then popping off the top element as required.

eg

    T sum()
    {
        Stack<T> tempStack = stack;
        T sum = 0;

        while (!tempStack.isEmpty())
        {
            sum += tempStack.pop();
        }

        return sum;
    }

Answer 3

It does not work because when you create your App object here

App<int> a(myStack);

You are creating a new Stack for the object a by copying your myStack . Pushing data to the variable myStack won't change the Stack<T> variable inside your object a .

To have the expected result, you need to change your class App so that it should have a pointer to a Stack<T> data member such as:

Stack<T> * stack;

After that, update your constructor to correspond your data member:

App(Stack<T> &stack) {
    this->stack = &stack;
}
T substract(){
    Stack<T> tempStack = *stack;
    T sum=1;
    for(int i=0; i<=stack->getTopLevel(); i++) {
        sum-=tempStack.peek();
        tempStack.pop();
    }
    return sum;
}
T sum(){
    Stack<T> tempStack = *stack;
    T sum=1;
    for(int i=0; i<=stack->getTopLevel(); i++) {
        sum+=tempStack.peek();
        tempStack.pop();
    }
    return sum;
}

That should do it. Also you are defining a NMAX 10 in your stack_base.h file and NMAX 5 in queque.h file. That limits the number of the elements in your stack. As far as your code implies queque.h is unnecessary. Remove the #include "queque.h" line and changing the line you are defining NMAX to something like #define NMAX 20 in the stack_base.h file. So that myStack could contain 20 elements. Your main function should look like this at the end:

int main(){
    Stack<int> myStack;
    App<int> a(myStack);
    int values[7] = {5, 2, 3, 1, 4, 8, 6};
    int values1[7] = {5, 2, 3, 1, 4, 8, 6};
    for(int i=0; i<8; i++) {
        myStack.push(values[i]);
        myStack.push(values1[i]);
    }
    cout<<a.sum()<<endl;
    return 0;
}

59 should be displayed which is 1 more than the summation of your elements since you initialized your sum variable to 1.