C++ 固定长度的队列

因为有需求，需要程序在内存大小保存不变来保存数据，但是数据的取用又是按队列的来操作，节约时间节约内存，但是c++基础又不太好.

#include <iostream>
#include <string>

using namespace std;


typedef struct NN {
    string data;
} Node;

class FixedQueue {
    public:
        int length;
        FixedQueue(int size) {
            this->size = size; // 容器的大小 
            this->init();
            // 分配内存 
            this->data = new Node[size];
        }
        void init() {
            this->length = this->startp = 0;
            this->endp = -1;
        }
　　　　 // 出队
        Node * pop() {
            if (!empty()) {
                int geti = this->startp;
                this->startp++;
                if (this->startp < 0) {
                    this->startp = this->size;
                } 
                this->length--;
                return &(this->data[geti]);
            }
            //cout << "队列为空！" << endl;
            return NULL;
        }
        // 相当于入队
        Node * getNode() {
            if (!full()) {
                this->endp = (this->endp+1)%(this->size);
                //cout << "正在获取一个节点： " << this->data[i].data  << endl;
                this->length++;
                //cout << "分配一个节点" << endl; 
                return &this->data[this->endp];
            }
            cout << "队列已满" << endl; 
            return NULL;
        }
        bool empty() {
            if (this->length == 0) {
                this->init();
                return true;
            }
            return false;
        }
        bool full() {
            return this->size == this->length;
        }
        void print() {
            cout << this->startp << ":" << this->endp << " > " << this->length << endl;
        }
    private:
        int startp;
        int endp;
        int size;
        Node *data;
};


int main() {
    
    FixedQueue q(7);
    cout << "固定队列已创建: " << q.length  << endl;
    
    Node* n = q.getNode();
    n->data = "111111111111111111";
    
    Node* n1 = q.getNode();
    n1->data = "2222222222";
    
    Node* n2 = q.getNode();
    n2->data = "33333333333333";
    
    Node* n3 = q.getNode();
    n3->data = "44444444444444444444";
    
    Node* n4 = q.getNode();
    n4->data = "555555555555555";
    
    Node* n5 = q.getNode();
    n5->data = "666666666666666666666666";
    
    
    Node* n6 = q.getNode();
    n6->data = "77777777777777";
    
    Node* n7 = q.getNode();
    
    // 出队列 
    while(!q.empty()) {
        cout << q.pop()->data << endl;
    }
    q.print();
    return 0;
}