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1. vector 常用成员函数的模拟实现

2. vector 常用成员函数实现后的测试

#include<assert.h>
#include<iostream>
#include<string>
using std::cout;
using std::endl;
using std::string;//自定义命名空间wch
namespace wch
{//vector要支持不同类型元素，所以用模板template<class T>class vector{public:typedef T* iterator;typedef const T* const_iterator;iterator begin(){return _start;}iterator end(){return _finish;}const_iterator begin() const{return _start;}const_iterator end() const{return _finish;}// vector<int> v(10, 1);//如果无函数vector(int n, const T& val = T())，//因为参数类型更匹配，会去调用vector(InputIterator first, InputIterator last)// 但是函数内部有解引用（*first），整形不可解引用，导致报错vector(size_t n, const T& val = T()){resize(n, val);}vector(int n, const T& val = T()){resize(n, val);}// [first, last)迭代器，采用区间初始化template<class InputIterator>vector(InputIterator first, InputIterator last){while (first != last){push_back(*first);++first;}}//由于声明时已经初始化给予了缺省参数，所以此处不写初始化列表初始化vector(){}//原始方法实现拷贝构造函数vector(const vector<T>& v){_start = new T[v.capacity()];//memcpy(_start, v._start, sizeof(T)*v.size());//浅拷贝，部分自定义类型无法达到目的//深拷贝for (size_t i = 0; i < v.size(); i++){_start[i] = v._start[i];}_finish = _start + v.size();_endofstorage = _start + v.capacity();}//现代方法拷贝构造/*vector(const vector<T>& v):_start(nullptr), _finish(nullptr), _endofstorage(nullptr){reserve(v.capacity());for (auto e : v){push_back(e);}}*/void swap(vector<T>& v){//注意这里用的是库函数swap，因为我们这里是在自己实现vector成员函数std::swap(_start, v._start);std::swap(_finish, v._finish);std::swap(_endofstorage, v._endofstorage);}// v1 = v2，赋值运算符重载vector<T>& operator=(vector<T> v){swap(v);return *this;}~vector(){if (_start){delete[] _start;_start = _finish = _endofstorage = nullptr;}}void reserve(size_t n){//要加判断，因为当n<capacity时，不需要做处理if (n > capacity()){//这里需要先保存大小，因为开辟新空间后，成员函数size里的地址_finish还指向销毁的旧空间，//无法正确完成_finish的更新size_t sz = size();T* tmp = new T[n];if (_start){//memcpy(tmp, _start, sizeof(T) * sz);//浅拷贝//深拷贝for (size_t i = 0; i < sz; i++){tmp[i] = _start[i];}delete[] _start;}_start = tmp;_finish = _start + sz;_endofstorage = _start + n;}}//缺省参数T()，当缺省参数为自定义类型，T()为匿名对象，会去调用构造函数//内置类型如：int与int()无差别void resize(size_t n, const T& val = T()){if (n < size()){_finish = _start + n;}else{reserve(n);//多余有效空间用val初始化while (_finish != _start + n){*_finish = val;++_finish;}}}void push_back(const T& x){/*if (_finish == _endofstorage){size_t newcapacity = capacity() == 0 ? 4 : capacity() * 2;reserve(newcapacity);}*_finish = x;++_finish;*/insert(end(), x);}void pop_back(){erase(--end());}size_t capacity() const{return _endofstorage - _start;}size_t size() const{return _finish - _start;}T& operator[](size_t pos){assert(pos < size());return _start[pos];}const T& operator[](size_t pos) const{assert(pos < size());return _start[pos];}//返回插入元素地址iterator insert(iterator pos, const T& x){assert(pos >= _start && pos <= _finish);if (_finish == _endofstorage){size_t len = pos - _start;// 解决pos迭代器失效问题size_t newcapacity = capacity() == 0 ? 4 : capacity() * 2;reserve(newcapacity);// 需要更新pos，因为扩容过后pos还指向旧空间，即解决pos迭代器失效问题pos = _start + len;}iterator end = _finish - 1;while (end >= pos){*(end + 1) = *end;--end;}*pos = x;++_finish;return pos;}//返回删除元素地址iterator erase(iterator pos){assert(pos >= _start && pos < _finish);iterator it = pos + 1;while (it != _finish){*(it - 1) = *it;++it;}--_finish;return pos;}private://给予缺省参数iterator _start = nullptr;iterator _finish = nullptr;iterator _endofstorage = nullptr;};void print(const vector<int>& v){for (auto e : v){cout << e << " ";}cout << endl;}void test_vector1(){vector<int> v1;v1.push_back(1);v1.push_back(2);v1.push_back(3);v1.push_back(4);v1.push_back(5);for (auto e : v1){cout << e << " ";}cout << endl;for (size_t i = 0; i < v1.size(); i++){v1[i]++;}for (auto e : v1){cout << e << " ";}cout << endl;print(v1);}void test_vector2(){vector<int> v1;v1.push_back(1);v1.push_back(2);v1.push_back(3);v1.push_back(4);v1.push_back(5);v1.push_back(5);v1.push_back(5);v1.push_back(5);for (auto e : v1){cout << e << " ";}cout << endl;v1.insert(v1.begin(), 100);for (auto e : v1){cout << e << " ";}cout << endl;/*vector<int>::iterator p = v1.begin() + 3;v1.insert(p, 300);*/vector<int>::iterator p = v1.begin() + 3;//v1.insert(p+3, 300);// insert以后迭代器可能会失效(扩容)// 记住，insert以后就不要使用这个形参迭代器了，因为他可能失效了v1.insert(p, 300);// 高危行为// *p += 10;for (auto e : v1){cout << e << " ";}cout << endl;}void test_vector3(){vector<int> v1;v1.push_back(1);v1.push_back(2);v1.push_back(2);v1.push_back(3);v1.push_back(4);v1.push_back(5);v1.push_back(6);for (auto e : v1){cout << e << " ";}cout << endl;auto it = v1.begin();while (it != v1.end()){if (*it % 2 == 0){it = v1.erase(it);}else{++it;}}//v1.erase(v1.begin());//auto it = v1.begin()+4;//v1.erase(it); erase以后，迭代器失效了，不能访问 vs进行强制检查，访问会直接报错//cout << *it << endl;//++it;//cout << *it << endl;for (auto e : v1){cout << e << " ";}cout << endl;}void test_vector4(){vector<int> v;v.resize(10, 0);for (auto e : v){cout << e << " ";}cout << endl;int i = 0;int j = int();//i = 0;int k = int(1);//k = 1;}void test_vector5(){vector<int> v;v.push_back(1);v.push_back(2);v.push_back(3);v.push_back(4);v.push_back(5);vector<int> v1(v);for (auto e : v1){cout << e << " ";}cout << endl;vector<int> v2;v2.resize(10, 1);v1 = v2;for (auto e : v1){cout << e << " ";}cout << endl;}void test_vector6(){vector<string> v;v.push_back("111111111111111111");v.push_back("222222222222222222");v.push_back("333333333333333333");v.push_back("444444444444444444");v.push_back("555555555555555555");for (auto& e : v){cout << e << " ";}cout << endl;vector<string> v1(v);for (auto& e : v1){cout << e << " ";}cout << endl;}void test_vector7(){vector<int> v(10, 1);vector<string> v1(10, "1111");vector<int> v2(10, 1);for (auto e : v){cout << e << " ";}cout << endl;vector<int> v3(v.begin(), v.end());for (auto e : v3){cout << e << " ";}cout << endl;string str("hello world");vector<char> v4(str.begin(), str.end());for (auto e : v4){cout << e << " ";}cout << endl;int a[] = { 16,2,77,29 };vector<int> v5(a, a + 4);for (auto e : v5){cout << e << " ";}cout << endl;}
}int main()
{//wch::test_vector1();//wch::test_vector2();//wch::test_vector3();//wch::test_vector4();//wch::test_vector5();//wch::test_vector6();wch::test_vector7();return 0;
}