c++ - 使模板类正常工作时出错

我正在尝试实现自己的minHeap，并且收到与模板类有关的错误

这是main.cpp:

#include <iostream>
#include"road.h"
#include"region.h"
#include"minHeap.h"

using namespace std;

int main()
{

//    int numCities;
    int numOldRoads;

    cin >> numOldRoads;

    minHeap<int> roadHeap(numOldRoads);

    roadHeap.push(1);
    roadHeap.push(4);
    roadHeap.push(5);
    roadHeap.push(2);
    roadHeap.push(7);
    roadHeap.push(6);
    roadHeap.push(3);
    roadHeap.push(9);
    roadHeap.push(8);

    int temp;

    for(int i = 0; i<numOldRoads; i++){
        temp = roadHeap.top();
        roadHeap.pop();
        cout << temp;
    }

    return 0;
}

这是头文件:

#ifndef MIN_HEAP
#define MIN_HEAP

template<class T>
class minHeap{

public:
    minHeap(int);
    void push(T);
    void pop();
    T top();
    void doubleHeapCap();
    bool isEmpty();

private:
    T *heap;
    int heapSize;
    int capacity;

};

#endif

这是minHeap的实现(也在 header 中，因为否则会给我错误):

#include"minHeap.h"

template<class T>
minHeap<T>::minHeap(int theCapacity = 10){

    if(theCapacity < 1) throw "Capacity must be >=1.";
    capacity = theCapacity;
    heapSize = 0;
    heap = new T[capacity + 1]; //heap [0] is not used

}

template<class T>
void minHeap<T>::push(const T& e){
//inserts e into min heap
    if(heapSize == capacity){ //doubles capacity if Heap is too small
        minHeap.doubleHeapCap;
        capacity *=2;
    }

    int currentNode == ++heapSize;

    while(currentNode != 1 && heap[currentNode/2] > e){
        //bubble up node
        heap[currentNode] = heap[currentNode/2]; //moves parent down
        currentNode /= 2; //moves current node
    }

    heap[currentNode] = e;

}

template<class T>
void minHeap<T>::pop(){
//Deletes smallest element from heap and restructures heap
    if(isEmpty()) throw "Heap is empty. Cannot delete.";

    //deelt smallest element
    heap[1].~T();

    //remove last element from heap
    T lastE = heap[heapSize--];

    //trick down to restructure heap
    int currentNode = 1; //root of heap
    int child = 2; // first child of heap

    while(child <= heapSize){

        //set child to smaller child of currentNode
        if(child < heapSize && heap[child] > heap[child+1]) child++;

        //can we put lastE in currenNode?
        if(lastE >= heap[child]) break; //yes we can

        //no we can't, Obama
        heap[currentNode] = heap[child]; //move child up
        currentNode = child; child *= 2; // move a level down
    }

    //after you finally find one, place the node in the corrent position
    heap[currentNode] = lastE;
}

template<class T>
bool minHeap<T>::isEmpty(){
//says whether or not hear is empty
    if(heapSize == 0) return 1;
    else return 0;
}

template<class T>
void minHeap<T>::doubleHeapCap(){

    int currentcapacity = this->capacity;
    int newCapacity = (this->capacity)*2;
    minHeap *temp;
    T *newHeap;

    //create a new heap with twic the size
    newHeap = new T[newCapacity + 1];

    //copy elements over
    for(int i=0; i<=capacity; i++){
        newHeap[i] = this->heap[i];
    }

    //delete the old heap
    temp = heap;
    heap = newHeap;
    newHeap = 0;

    delete[] temp;
}

这是错误:

In instantiation of 'void minHeap<T>::doubleHeapCap() [with T = int]':
required from 'void minHeap<T>::push(const T&) [with T = int]'
required from here
error: cannot convert 'int*' to 'minHeap<int>*' in assignment|
warning: unused variable 'currentcapacity' [-Wunused-variable]|

我几乎从我的数据结构书中复制了代码并进行了修改(书中显示了Max Heap的实现，我对最小堆很感兴趣)。

如您所见，我现在尝试使用的主要方法是打印出我尝试压入最小堆的升序整数列表。

我想我不完全了解如何实现模板类功能。

最佳答案

在类声明中，您需要:

T *heap;

在doubleHeapCap中，您有以下内容:

minHeap *temp;

// code...

temp = heap;

如果T是int，则您尝试将int*(heap)分配给minHeap<int>*(temp)。基本上，也将temp变成T*，它应该可以工作。或者，您可以完全省掉temp并编写:

std::swap(heap, newHeap);
delete[] newHeap;

minheap

c++ - 使模板类正常工作时出错