面试：vector类的简单实现

vector类的简单实现

  1 #include 
  2 #include 
  3 #include 
  4 #include 
  5 using namespace std;
  6 
  7 template
  8 class MyVector{
  9 private:
 10     const size_t WALK_LENGTH = 16;
 11 
 12     T* _array;
 13     size_t _size;
 14     size_t _capacity;
 15 public:
 16     MyVector():_array(nullptr),_size(0),_capacity(0){}
 17 
 18     MyVector(size_t n,T value = 0){
 19         _capacity = WALK_LENGTH;
 20         while(n > _capacity){
 21             _capacity += WALK_LENGTH;
 22         }
 23         _array = new T[_capacity];
 24         _size = n;
 25         while(n--){
 26             _array[n] = value;
 27         }
 28     }
 29 
 30     MyVector(const MyVector& other){
 31         this->_size = other._size;
 32         this->_capacity = other._size;
 33         this->_array = new T[_capacity];
 34         memcpy(_array,other._array,sizeof(T)*_capacity);
 35     }
 36 
 37     ~MyVector(){
 38         if(this->_array){
 39             delete [] this->_array;
 40         }
 41     }
 42 
 43     MyVector& operator=(const MyVector& other){
 44         if(this == &other){
 45             return *this;
 46         }
 47         if(this->_array){
 48             delete [] _array;
 49         }
 50         this->_array = new T[other._capacity];
 51         this->_capacity = other._capacity;
 52         this->_size = other._size;
 53         memcpy(this->_array,other._array,_capacity*sizeof(T));
 54         return *this;
 55     }
 56 
 57     T operator[](size_t index){
 58         assert(index < this->_size);
 59         return _array[index];
 60     }
 61 
 62     size_t size(){
 63         return this->_size;
 64     }
 65     size_t capacity(){
 66         return this->_capacity;
 67     }
 68     bool isEmpty(){
 69         return this->_size == 0;
 70     }
 71 
 72     void push_back(const T& t){
 73         if(this->_size == this->_capacity){
 74             T* tmp = this->_array;
 75             this->_array = new T[_capacity+WALK_LENGTH];
 76             memcpy(this->_array,tmp,this->_size*sizeof(T));
 77             this->_capacity += WALK_LENGTH;
 78             delete [] tmp;
 79         }
 80 
 81         this->_size += 1;
 82         _array[_size -1] = t;
 83     }
 84 
 85     void insert(size_t pos,const T& t){
 86         assert(pos <= _size);
 87 
 88         if(_size == _capacity){
 89             _capacity += WALK_LENGTH;
 90             T* tmp = _array;
 91             _array = new T[_capacity];
 92             memcpy(_array,tmp,sizeof(T)*_size);
 93             delete [] tmp;
 94         }
 95         for(size_t i = _size-1;i>=pos;i--){
 96             _array[i+1] = _array[i];
 97         }
 98         _array[pos] = t;
 99         _size += 1;
100     }
101 
102     void erase(size_t pos){
103         assert(pos < _size);
104 
105         for(size_t i=pos+1;i<_size;i++){
106             _array[i-1] = _array[i];
107         }
108         _size--;
109     }
110 };
111 
112 
113 int main(){
114     MyVector<int> v(3);
115     v.push_back(4);
116     v.push_back(10);
117     v.insert(1,100);
118     v.erase(2);
119     std::cout << v[3] << std::endl;
120     std::cout << v.capacity() << std::endl;
121     std::cout << v.size() << std::endl;
122     for(size_t i=0;i){
123         std::cout << v[i] << ",";
124     }
125     std::cout << std::endl;
126     return 0;
127 }

 

转载于:https://www.cnblogs.com/wxquare/p/4986552.html