无法在 c++ 中为容器类获取插入和附加函数以正常工作

我正在尝试通过使用实现文件中的插入和附加函数排列它们来将数字存储在我的驱动程序类中。插入函数应该将数字向左或较小的位置移动，并附加移动到数据数组中的右侧或更高位置。这是实现之一：

#include "Lab1A.h"
#include <iostream>
#include <cassert>
#include <algorithm>
sequence::sequence() {
    used = 0;
    current_index = 0;
}
// MUTATOR MEMBER FUNCTIONS 
//Postcondition: The first item in the sequence becomes the current item
void sequence::start() {
    current_index = 0;
    //Precondition: is_item returns true.
    //Postcondition: If the current item was already the last item in the
    //sequence, then there is no longer any current item. Otherwise, the new
    //current item is the item immediately after the original current item.
}
void sequence::advance() {
    if (is_item()) {
        current_index++;
    }
}
//Precondition: size( ) < CAPACITY.
//Postcondition: A new copy of entry has been inserted in the sequence
//before the current item. If there was no current item, then the new entry 
//has been inserted at the front of the sequence (position 0). In either      //case, the newly inserted item is now the current item of the sequence.
void sequence::insert(const value_type& entry) {
    if (size() < CAPACITY) {
        data[used] = data[used - 1];
        data[used] = entry;
        data[current_index] = entry;
        used++;
    }
    if (is_item() == false) {
        data[used] = entry;
        data[used] = data[used + 1];
    }
}
//Precondition: size( ) < CAPACITY.
//Postcondition: A new copy of entry has been inserted in the sequence //after the current item. If there was no current item, then the new entry //has been attached to the end of the sequence. In either case, the newly
//inserted item is now the current item of the sequence.
void sequence::attach(const value_type& entry) {
    if (size() < CAPACITY) {
        data[used] = data[used + 1];
        data[used] = entry;
        data[current_index] = entry;
        used++;
    }
    if (is_item() == false) {
        data[used] = entry;
        data[used] = data[used + 1];
    }
}
//Precondition: is_item returns true.
//Postcondition: The current item has been removed from the sequence, and //the item after this (if there is one) is now the new current item.
void sequence::remove_current() {
    int i;
    if (is_item()) {
        current_index--;
        data[i] = data[current_index];
    }
}
// ACCESSOR MEMBER FUNCTIONS
//Postcondition: The value returned is the number of items in the         
//sequence.
int sequence::size() const {
    return used;
}
//Postcondition: A true return value indicates that there is a valid
//"current" item that may be retrieved by invoking the current
//member function below. A false return value indicates that
//there is no valid current item.
bool sequence::is_item() const {
    return (current_index < used);
}
//Precondition: is_item( ) returns true.
//Postcondition: The item returned is the current item in the sequence.
sequence::value_type sequence::current() const {
    return data[current_index];
}
void sequence::print() {
    for (int j = 0; j < used; j++) {
        cout << data[j] << " ";
    }
}

驱动程序文件：

#include <iostream>
#include <cstdlib>  
#include "Lab1Aimplementation.cpp"
using namespace std;
int main()
{
    sequence numbers;
    numbers.insert(21);
    numbers.attach(33);
    numbers.insert(22);
    numbers.print();
    return 0;
}

我正在尝试获取此输出：21 22 33相反，我得到：22 33 22

可能将sequence声明为 OP 没有附加：

class sequence
{
    using index_type = int;
    using value_type = size_t;

    static const index_type CAPACITY = 1024;
    value_type data[CAPACITY];
    index_type used;
    index_type current_index;
public:
    sequence();
    void start();
    void advance();
    void insert(const value_type& entry);
    void attach(const value_type& entry);
    void remove_current();
    int size() const;
    bool is_item() const;
    value_type current() const;
    void print();
};