如何在 C++ 中创建自动类型的模板 Class 对象？

Question

我是一名学习者，我使用的逻辑可能不正确（因为我仍处于学习阶段）。我使用模板在 C++ 中创建了一个简单的堆排序代码。在主函数中，从堆 class 中为每种数据类型调用每个函数都会创建相同行的副本。所以，我想使用指针对象为所有数据类型编写通用函数调用，然后该指针对象将引用该堆的相应对象 class。

这是我出错的主要功能代码部分。

Heap<auto> *obj;
Heap<int> intOb(n);
Heap<char> charOb(n);
Heap<float> floatOb(n);

if (dataType == 1) {
    obj = &intOb;
} else if (dataType == 2) {
    obj = &charOb;

} else if (dataType == 3) {
    obj = &floatOb;

} else {
    cout << "Wrong Data Type\n";
    exit(101); }

obj->inputArray();
cout << "---------------------------------------------------------\n";
cout << "The Array you have entered is ";
obj->printArray();
obj->buildMaxHeap();
cout << "The Heapified Array is ";
obj->printArray();
obj->heapSort();
cout << "The Array After Heap Sort is ";
obj->printArray();
cout << "The Total no of comparisons is " << obj->counter << endl;

如果我只是在 if else 循环中调用所有这些函数，代码将会重复。为了避免它们，我创建了一个 auto 类型的指针对象。但是，模板中不允许使用 auto。如果我用 int 替换 auto，那么对 char 和 float 的引用会出错。

有什么方法可以调整对象的创建，这样我就不必在 if else 循环中一次又一次地重复这些行了吗？

如果我的问题得不到解决，我将不得不多次重复相同的行，就像给定的代码一样。

if (dataType == 1) {
    Heap<int> obj(n);
    obj.inputArray();
    cout << "---------------------------------------------------------\n";
    cout << "The Array you have entered is ";
    obj.printArray();
    obj.buildMaxHeap();
    cout << "The Heapified Array is ";
    obj.printArray();
    obj.heapSort();
    cout << "The Array After Heap Sort is ";
    obj.printArray();
    cout << "The Total no of comparisons is " << obj.counter << endl;

} else if (dataType == 2) {
    Heap<char> obj(n);
    obj.inputArray();
    cout << "---------------------------------------------------------\n";
    cout << "The Array you have entered is ";
    obj.printArray();
    obj.buildMaxHeap();
    cout << "The Heapified Array is ";
    obj.printArray();
    obj.heapSort();
    cout << "The Array After Heap Sort is ";
    obj.printArray();
    cout << "The Total no of comparisons is " << obj.counter << endl;

} else if (dataType == 3) {
    Heap<float> obj(n);
    obj.inputArray();
    cout << "---------------------------------------------------------\n";
    cout << "The Array you have entered is ";
    obj.printArray();
    obj.buildMaxHeap();
    cout << "The Heapified Array is ";
    obj.printArray();
    obj.heapSort();
    cout << "The Array After Heap Sort is ";
    obj.printArray();
    cout << "The Total no of comparisons is " << obj.counter << endl;

} else { cout << "Wrong Data Type\n"; }
if (dataType == 1) {
    Heap<int> obj(n);
    obj.inputArray();
    cout << "---------------------------------------------------------\n";
    cout << "The Array you have entered is ";
    obj.printArray();
    obj.buildMaxHeap();
    cout << "The Heapified Array is ";
    obj.printArray();
    obj.heapSort();
    cout << "The Array After Heap Sort is ";
    obj.printArray();
    cout << "The Total no of comparisons is " << obj.counter << endl;

} else if (dataType == 2) {
    Heap<char> obj(n);
    obj.inputArray();
    cout << "---------------------------------------------------------\n";
    cout << "The Array you have entered is ";
    obj.printArray();
    obj.buildMaxHeap();
    cout << "The Heapified Array is ";
    obj.printArray();
    obj.heapSort();
    cout << "The Array After Heap Sort is ";
    obj.printArray();
    cout << "The Total no of comparisons is " << obj.counter << endl;

} else if (dataType == 3) {
    Heap<float> obj(n);
    obj.inputArray();
    cout << "---------------------------------------------------------\n";
    cout << "The Array you have entered is ";
    obj.printArray();
    obj.buildMaxHeap();
    cout << "The Heapified Array is ";
    obj.printArray();
    obj.heapSort();
    cout << "The Array After Heap Sort is ";
    obj.printArray();
    cout << "The Total no of comparisons is " << obj.counter << endl;

} else { cout << "Wrong Data Type\n"; }

Answer 1

使用（模板）函数完成所有主要工作，并将Heap模板实例传递（引用）给函数。

可能是这样的：

template<typename T>
void work_on_heap(Heap<T> const& heap)
{
    heap.inputArray();
    cout << "---------------------------------------------------------\n";
    cout << "The Array you have entered is ";
    heap.printArray();
    heap.buildMaxHeap();
    cout << "The Heapified Array is ";
    heap.printArray();
    heap.heapSort();
    cout << "The Array After Heap Sort is ";
    heap.printArray();
    cout << "The Total no of comparisons is " << heap.counter << endl;
}

然后像这样打电话：

if (dataType == 1) {
    work_on_heap(Heap<int>(n));
} else if (dataType == 2) {
    work_on_heap(Heap<char>(n));
} else if (dataType == 3) {
    work_on_heap(Heap<float>(n));
} else {
    cout << "Wrong Data Type\n";
    exit(1);
}

如何在 C++ 中创建自动类型的模板 Class 对象？

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