Tree Template Class Implementation for C++

I have not done any parameter checking, however I think the meat of the class is there. Let me know what you think.

#include 
#include 
using namespace std;

template
class TreeNode {

private:

    T* data;
    TreeNode* parent;
    vector* > children;

public:

    TreeNode(TreeNode* parent, T data);
    ~TreeNode();

    T& getData() const;
    void setData(const T& data);
    void addChild(const T& data);
    void removeChild(const size_t& indx);
    TreeNode* findChild(const T& data) const;
    TreeNode* getChild(const size_t& indx) const;
    TreeNode* getParent() const;
    int getNumChildren() const;

};

template
TreeNode::TreeNode(TreeNode* parent, T data) : parent(parent) {
    this->data = new T(data);
}

template
TreeNode::~TreeNode() {
    delete data;
    for(TreeNode* childNode : children)
        delete childNode;
}

template
T& TreeNode::getData() const {
    return *this->data;
}

template
void TreeNode::setData(const T& data) {
    *this->data = data;
}

template
void TreeNode::addChild(const T& data) {
    children.push_back(new TreeNode(this, data));
}

template
void TreeNode::removeChild(const size_t& indx) {
    children.erase(children.begin()+indx);
}

template
TreeNode* TreeNode::findChild(const T& data) const {
    for(int i=0; igetData() == data)
            return children[i];
    return NULL;
}

template
TreeNode* TreeNode::getChild(const size_t& indx) const {
    return children[indx];
}

template
TreeNode* TreeNode::getParent() const {
    return parent;
}

template
int TreeNode::getNumChildren() const {
    return children.size();
}

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Do not get in the habit of using using namespace std.

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Since you're using ` for size_t, you should make it std::size_t for C++.

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Since you define your own destructor, you should also overload the copy constructor and the assignment operator. This is known as The Rule of Three in C++. This is especially important in the case of raw pointers as data members as the compiler-provided copy constructor and assignment operator will only copy the pointer (shallow copy), not the data (deep copy).

You should also follow Dieter's advice (in the comments): use T data instead of T* data, and remove thenew/delete. Use as little manual memory allocation as possible in C++.

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You're using a range-based for-loop in the destructor, which must mean you're using C++11. Bearing this in mind, one change you should make is using nullptr instead of NULL`.

StackExchange Code Review Q#47395, answer score: 8