使用模板构造函数创建模板类对象 [英] Creating a template class object using a template constructor

问题描述

我无法从模板类创建类对象，在该类中，我需要构造函数也应作为模板并在创建对象时接受参数。但是，当我尝试创建对象时，收到一条错误消息，指出我所引用的不存在。

I'm having trouble creating a class object from a template class in which I need the constructor to also be a template and accept a parameter when the object is created. However, when I attempt to create the object, I receive an error message stating that I'm referencing something that doesn't exist.

这是我的代码：

using namespace std;
#include <cstdlib>

template <class Node_Type>
class BinaryTree 
{
public:
    BinaryTree(Node_Type);
    BinaryTree(Node_Type, Node_Type);
    BinaryTree(Node_Type, Node_Type, Node_Type);
    bool isEmpty();
    Node_Type info();
    Node_Type inOrder();
    Node_Type preOrder();
    Node_Type postOrder();


private:
    struct Tree_Node
{
    Node_Type Node_Info;
    BinaryTree<Node_Type> *left;
    BinaryTree<Node_Type> *right;
};

Tree_Node *root;

};

#endif

和我的.cpp：

template <class Node_Type>
BinaryTree<Node_Type>::BinaryTree(Node_Type rootNode) {

    root = rootNode;
    root->left = NULL;
    root->right = NULL;

}

.cpp还有更多功能，但这只是其他功能无关的成员。上面显示的构造函数是我无法使用的。

There's more to the .cpp, but it's just other function members that are irrelevant. My constructor shown above is what I can't get to work.

在我的主机中，我试图通过调用声明我的对象：

In my main, I'm attempting to declare my object with the call:

BinaryTree<char> node('a');

但是当我尝试这样做时，我收到一条错误消息，指出：

but when I try this, I get an error message stating:

undefined reference to `BinaryTree<char>::BinaryTree(char)'

我已经尝试了两天。我已经搜寻了所有我能想到的主题，并且在没有帮助的情况下阅读了关于Stack Overflow和其他资源的无数示例。谁能解释我的问题是什么？我知道该怎么做，如果语法在C ++中不是那么荒谬，我现在就结束了。

I've been trying to figure this out for two days now. I've Googled every topic I can think of and read countless examples on Stack Overflow and other sources with no help. Can anyone please explain what my problem is? I know how to do my project, and I'd be finished by now if the syntax wasn't so ridiculous in C++. Thanks in advance!

推荐答案

模板代码在实例化时应该可见，这意味着函数的定义也必须是在标题中。

Template code should be visible at the time of instantiation, meaning that the definition of the functions must also be in the header.

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