c++实现Myvector。

c++实现一个自己的vector。我们用到c++的类、重载、模板类。

#pragma once
#include
#include
#include
template
class MyVector
{
public:
	MyVector(int size = 10);
	~MyVector();

	//访问
	T& at(int index) const;
	T& front() const;
	T& back() const;
	T& operator[](int index);


	//容量
	bool empty() const;
	int size() const;
	int capacity() const;
	

	//修改
	void clear();
	void insert(int index, const T& d);
	void remove(int index);
	void push_back(const T& d);
	void pop_back();

private:
	T* data;
	int length;
	int current_pos;

};
template
MyVector::MyVector(int size) :length(size), current_pos(0)
{
	if (data != nullptr)
	{
		delete[] data;
		data = nullptr;
	}
	data = new T[length];
	memset(data, 0, length * sizeof(T));
}
template
MyVector::~MyVector()
{
	if (data != nullptr)
	{
		delete[] data;
		data = nullptr;
	}
}

template
T& MyVector::at(int index) const
{
	assert(index > 0 || index < current_pos);
	return data[index];
}

template
T& MyVector::front() const
{
	assert(current_pos > 0);
	return data[0];
}

template
T& MyVector::back() const
{
	assert(current_pos > 0);
	return data[current_pos - 1];
}

template
T& MyVector::operator[](int index)
{
	assert(index > 0 || index < current_pos);
	return data[index];
}

template
bool MyVector::empty() const
{
	return current_pos == 0 ? true : false;
}

template
int MyVector::size() const
{
	return current_pos;
}

template
int MyVector::capacity() const
{
	return length;
}

template
void MyVector::clear()
{
	current_pos = 0;
}

template
void MyVector::insert(int index, const T& d)
{
	assert(index > 0 || index < current_pos);
	if (current_pos == length)
	{
		T* temp = new T[length + 10];
		memset(temp, 0, (length + 10) * sizeof(T));
		memcpy(temp, data, length * sizeof(T));
		length += 10;
		delete[]data;
		data = nullptr;
		data = temp;
	}

	memcpy(data + index + 1, data + index, (length - index) * sizeof(T));
	data[index] = d;

	// 当前数组指针 +1
	current_pos++;
}
template
void MyVector::remove(int index)
{
	assert(index > 0 || index < current_pos);

	memcpy(data + index, data + index + 1, (current_pos - index) * sizeof(T));
	current_pos--;
}



template
void MyVector::push_back(const T& d)
{
	// 检查当前数组大小是否可用
	if (current_pos == length) {
		// 扩容，每次扩容 10 个数据大小的空间
		T* temp = new T[length + 10];
		memset(temp, 0, (length + 10) * sizeof(T));
		memcpy(temp, data, length * sizeof(T));
		length += 10;
		delete[] data;
		data = nullptr;
		data = temp;
	}

	// 插入数据
	data[current_pos] = d;

	// 当前数组指针 +1
	current_pos++;

}
template
void MyVector::pop_back()
{
	assert(current_pos > 0);
	current_pos--;
}

main,cpp

#include 
#include "MyVector.h"

using namespace std;


int main()
{
	MyVector vec;
	for (int i = 0; i < vec.capacity(); i++)
		vec.push_back(i);
	vec.push_back(10);

	cout << "capacity: " << vec.capacity() << endl;
	for (int i = 0; i < vec.size(); i++)
		cout << vec.at(i) << ", ";
	cout << endl;

	vec.insert(0, 5);
	vec.insert(1, 15);
	for (int i = 0; i < vec.size(); i++)
		cout << vec[i] << ", ";
	cout << endl;

	vec.remove(1);
	vec.pop_back();
	for (int i = 0; i < vec.size(); i++)
		cout << vec[i] << ", ";
	cout << endl;

	cout << "front: " << vec.front() << ", back: " << vec.back() << endl;

	return 0;
}