代碼如下:

#pragma once #include <iostream> #include <assert.h> using namespace std;template<typename T> class Vector { public:typedef T* iterator;typedef const T* const_iterator;Vector() :_start(nullptr), _finish(nullptr), _endOfStorage(nullptr) {};Vector(int n, const T &val = T()) :_start(new T[n]), _finish(_start + n), _endOfStorage(_finish){for (int i = 0; i < n; i++){_start[i] = val;}}/*使用新的迭代器的原因是使傳入的迭代器可以是任意類型的，如果使用Vector的迭代器，那么傳入的迭代器的類型只能和Vector的類型一樣，這里拿string舉例，創建一個char類型的Vector，但是傳入的迭代器并不是char類型的，可以是字符數組的迭代器或者是string的迭代器。只要通過解引用是char類型就可以例如:string str = "Hello Wecccccccc";Vector<char> v4(str.begin(), str.end());*/template<typename InputIterator>Vector(InputIterator first, InputIterator last) :_start(nullptr), _finish(nullptr), _endOfStorage(nullptr){while (first != last){push_back(*first);++first;}}~Vector(){if (_start){delete[] _start;_start = _finish = _endOfStorage = nullptr;}}size_t size()const{return _finish - _start;}size_t capacity()const{return _endOfStorage - _start;}void push_back(const T&val){if (_finish == _endOfStorage){size_t newC = _endOfStorage == nullptr ? 1 : 2 * capacity();reserve(newC);}*_finish = val;++_finish;}//通過memcpy內存拷貝(淺拷貝),會造成二次釋放內存的情況，不安全，會報異常。/*void reserve(size_t n){if (n > capacity()){size_t sz = size();T *tmp = new T[n];if (_start != nullptr){memcpy(tmp, _start, sizeof(T) * size());delete[] _start;}_start = tmp;_finish = _start + sz;_endOfStorage = _start + n;}}*///深拷貝void reserve(size_t n){if (n > capacity()){size_t sz = size();T *tmp = new T[n];if (_start != nullptr){for (size_t i = 0; i < sz; i++){tmp[i] = _start[i];}delete[]_start;}_start = tmp;_finish = _start + sz;_endOfStorage = _start + n;}}iterator begin(){return _start;}iterator end(){return _finish;}const_iterator begin() const{return _start;}const_iterator end()const{return _finish;}T&operator[](size_t pos){assert(pos < size());return _start[pos];}const T&operator[](size_t pos) const{assert(pos < size());return _start[pos];}void resize(size_t n, const T&val = T()){if (n > capacity()){reserve(n);}if (n > size()){while (_finish != _start + n){*_finish = val;++_finish;}}_finish = _start + n;}void insert(iterator pos, const T &val){assert(pos >= _start || pos < _finish);if (_finish == _endOfStorage){size_t offset = pos - _start;size_t newC = _endOfStorage == nullptr ? 1 : 2 * capacity();reserve(newC);pos = _start + offset;}iterator end = _finish;while (end != pos){*end = *(end - 1);--end;}*pos = val;++_finish;}iterator erase(iterator pos){assert(pos >= _start || pos < _finish);iterator start = pos + 1;while (start != _finish){*(start - 1) = *start;++start;}--_finish;return pos + 1; //返回值：指向刪除元素的下一個元素。}void pop_back(){if (size() > 0) erase(end() - 1);}private:iterator _start;iterator _finish;iterator _endOfStorage; };template<typename T> void PrintVector(Vector<T> &vec) {typename Vector<T>::iterator it = vec.begin();while (it != vec.end()){cout << *it;++it;}cout << endl; }template<typename T> void PrintVectorFor(Vector<T> &vec) {for (auto &e : vec){cout << e;}cout << endl; }

測試代碼如下:

#include <iostream> #include <algorithm> #include "Vector.h" using namespace std;int main() {Vector<int>v1;Vector<int>v2(3,5);Vector<char>v3(5);cout << v1.size() << endl;cout << v1.capacity() << endl;cout << v2.size() << endl;cout << v2.capacity() << endl;cout << v3.size() << endl;cout << v3.capacity() << endl;string str = "Hello Wecccccccc";Vector<char> v4(str.begin(), str.end());v4.push_back('1');v4.push_back('2');v4.push_back('3');v4.reserve(100);cout << v4.size() << endl;cout << v4.capacity() << endl;PrintVector(v4);PrintVectorFor(v4);v4.resize(3);PrintVector(v4);v4.resize(4, '4');PrintVector(v4);Vector<int>v5;v5.push_back(2);v5.push_back(3);v5.push_back(5);v5.push_back(6);v5.insert(v5.begin(), 1);PrintVector(v5);v5.insert(v5.begin() + 3, 4);PrintVector(v5);v5.insert(v5.end(), 7);PrintVector(v5);v5.erase(v5.begin());PrintVector(v5);v5.erase(v5.end() - 1);PrintVector(v5);v5.pop_back();PrintVector(v5);Vector<int>::iterator it = find(v5.begin(), v5.end(), 5);if (it != v5.end()){cout << *it << endl;}else cout << "not find" << endl;it = find(v5.begin(), v5.end(), 1);if (it != v5.end()){cout << *it << endl;}else cout << "not find" << endl;return 0; }

測試結果:

總結

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