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  1. #include <cstddef>
  2. #include <iostream>
  3. #include <iterator>
  4. #include <algorithm>
  5.  
  6. template<typename T>
  7. class my_array{
  8.     T* data_;
  9.     std::size_t size_;
  10.  
  11. public:
  12.  
  13.     // ---------------------------------
  14.     // Forward declaration
  15.     // ---------------------------------
  16.     class const_iterator;
  17.  
  18.     // ---------------------------------
  19.     // iterator class
  20.     // ---------------------------------
  21.     class iterator: public std::iterator<std::random_access_iterator_tag, T>
  22.     {
  23.     public:
  24.         iterator(): p_(NULL) {}
  25.         iterator(T* p): p_(p) {}
  26.         iterator(const iterator& other): p_(other.p_) {}
  27.         const iterator& operator=(const iterator& other) {p_ = other.p_; return other;}
  28.  
  29.         iterator& operator++()    {p_++; return *this;} // prefix++
  30.         iterator  operator++(int) {iterator tmp(*this); ++(*this); return tmp;} // postfix++
  31.         iterator& operator--()    {p_--; return *this;} // prefix--
  32.         iterator  operator--(int) {iterator tmp(*this); --(*this); return tmp;} // postfix--
  33.  
  34.         void     operator+=(const std::size_t& n)  {p_ += n;}
  35.         void     operator+=(const iterator& other) {p_ += other.p_;}
  36.         iterator operator+ (const std::size_t& n)  {iterator tmp(*this); tmp += n; return tmp;}
  37.         iterator operator+ (const iterator& other) {iterator tmp(*this); tmp += other; return tmp;}
  38.  
  39.         void        operator-=(const std::size_t& n)  {p_ -= n;}
  40.         void        operator-=(const iterator& other) {p_ -= other.p_;}
  41.         iterator    operator- (const std::size_t& n)  {iterator tmp(*this); tmp -= n; return tmp;}
  42.         std::size_t operator- (const iterator& other) {return p_ - other.p_;}
  43.  
  44.         bool operator< (const iterator& other) {return (p_-other.p_)< 0;}
  45.         bool operator<=(const iterator& other) {return (p_-other.p_)<=0;}
  46.         bool operator> (const iterator& other) {return (p_-other.p_)> 0;}
  47.         bool operator>=(const iterator& other) {return (p_-other.p_)>=0;}
  48.         bool operator==(const iterator& other) {return  p_ == other.p_; }
  49.         bool operator!=(const iterator& other) {return  p_ != other.p_; }
  50.  
  51.         T& operator[](const int& n) {return *(p_+n);}
  52.         T& operator*() {return *p_;}
  53.         T* operator->(){return  p_;}
  54.  
  55.     private:
  56.         T* p_;
  57.  
  58.         friend class const_iterator;
  59.     };
  60.  
  61.     // ---------------------------------
  62.     // const_iterator class
  63.     // ---------------------------------
  64.     class const_iterator: public std::iterator<std::random_access_iterator_tag, T>
  65.     {
  66.     public:
  67.         const_iterator(): p_(NULL) {}
  68.         const_iterator(const T* p): p_(p) {}
  69.         const_iterator(const iterator& other): p_(other.p_) {}
  70.         const_iterator(const const_iterator& other): p_(other.p_) {}
  71.         const const_iterator& operator=(const const_iterator& other) {p_ = other.p_; return other;}
  72.         const const_iterator& operator=(const iterator& other) {p_ = other.p_; return other;}
  73.  
  74.         const_iterator& operator++()    {p_++; return *this;} // prefix++
  75.         const_iterator  operator++(int) {const_iterator tmp(*this); ++(*this); return tmp;} // postfix++
  76.         const_iterator& operator--()    {p_--; return *this;} // prefix--
  77.         const_iterator  operator--(int) {const_iterator tmp(*this); --(*this); return tmp;} // postfix--
  78.  
  79.         void           operator+=(const std::size_t& n)              {p_ += n;}
  80.         void           operator+=(const const_iterator& other)       {p_ += other.p_;}
  81.         const_iterator operator+ (const std::size_t& n)        const {const_iterator tmp(*this); tmp += n; return tmp;}
  82.         const_iterator operator+ (const const_iterator& other) const {const_iterator tmp(*this); tmp += other; return tmp;}
  83.  
  84.         void           operator-=(const std::size_t& n)              {p_ -= n;}
  85.         void           operator-=(const const_iterator& other)       {p_ -= other.p_;}
  86.         const_iterator operator- (const std::size_t& n)        const {const_iterator tmp(*this); tmp -= n; return tmp;}
  87.         std::size_t    operator- (const const_iterator& other) const {return p_ - other.p_;}
  88.  
  89.         bool operator< (const const_iterator& other) const {return (p_-other.p_)< 0;}
  90.         bool operator<=(const const_iterator& other) const {return (p_-other.p_)<=0;}
  91.         bool operator> (const const_iterator& other) const {return (p_-other.p_)> 0;}
  92.         bool operator>=(const const_iterator& other) const {return (p_-other.p_)>=0;}
  93.         bool operator==(const const_iterator& other) const {return  p_ == other.p_; }
  94.         bool operator!=(const const_iterator& other) const {return  p_ != other.p_; }
  95.  
  96.         const T& operator[](const int& n) const {return *(p_+n);}
  97.         const T& operator*()  const {return *p_;}
  98.         const T* operator->() const {return  p_;}
  99.  
  100.     private:
  101.         const T* p_;
  102.     };
  103.  
  104.     my_array()
  105.         : data_(NULL), size_(0)
  106.     {}
  107.     my_array(std::size_t size)
  108.         : data_(new T[size]), size_(size)
  109.     {}
  110.     my_array(const my_array<T>& other){
  111.         size_ = other.size_;
  112.         data_ = new T[size_];
  113.         for (std::size_t i = 0; i<size_; i++)
  114.             data_[i] = other.data_[i];
  115.     }
  116.     my_array(const const_iterator& first, const const_iterator& last){
  117.         size_ = last - first;
  118.         data_ = new T[size_];
  119.  
  120.         for (std::size_t i = 0; i<size_; i++)
  121.             data_[i] = first[i];
  122.     }
  123.  
  124.     ~my_array(){
  125.         delete [] data_;
  126.     }
  127.     const my_array<T>& operator=(const my_array<T>& other){
  128.         size_ = other.size_;
  129.         data_ = new T[size_];
  130.         for (std::size_t i = 0; i<size_; i++)
  131.             data_[i] = other.data_[i];
  132.         return other;
  133.     }
  134.     const T& operator[](std::size_t idx) const {return data_[idx];}
  135.     T& operator[](std::size_t& idx) {return data_[idx];}
  136.     std::size_t size(){return size_;}
  137.  
  138.     iterator begin(){ return iterator(data_); }
  139.     iterator end()  { return iterator(data_+size_); }
  140.     const_iterator begin() const{ return const_iterator(data_); }
  141.     const_iterator end() const  { return const_iterator(data_+size_);}
  142. };
  143.  
  144. template<typename T>
  145. void print(T t) {
  146.     std::cout << t << std::endl;
  147. }
  148.  
  149. int main(){
  150.  
  151.     int list [] = {1, 3, 5, 2, 4, 3, 5, 10, 10};
  152.     my_array<int> a(list, list+sizeof(list)/sizeof(int));
  153.  
  154.     // works!
  155.     for (my_array<int>::const_iterator it = a.begin(), end = a.end();
  156.          it != end; ++it)
  157.         std::cout << ' ' << *it;
  158.     std::cout << std::endl;
  159.  
  160.     // works!
  161.     std::for_each(a.begin(), a.end(), print<int>);
  162.     std::cout << std::endl;
  163.  
  164.     // works!
  165.     my_array<int> b(a.size());
  166.     std::copy(a.begin(), a.end(), b.begin());
  167.  
  168.     // works!
  169.     my_array<int>::iterator end = std::remove(a.begin(), a.end(), 5);
  170.     std::for_each(a.begin(), end, print<int>);
  171.     std::cout << std::endl;
  172.  
  173.     // works!
  174.     std::random_shuffle(a.begin(), end);
  175.     std::for_each(a.begin(), end, print<int>);
  176.     std::cout << std::endl;
  177.  
  178.     // works!
  179.     std::cout << "Counts of 3 in array = " << std::count(a.begin(), end, 3) << std::endl << std::endl;
  180.  
  181.     // works!
  182.     std::sort(a.begin(), end);
  183.     std::for_each(a.begin(), end, print<int>);
  184.     std::cout << std::endl;
  185.  
  186.     // works!
  187.     if (!std::binary_search(a.begin(), a.end(), 5))
  188.         std::cout << "Removed!" << std::endl;
  189.  
  190.     return 0;
  191. }
  192.  
Success #stdin #stdout 0s 2988KB
comments (?)
stdin 
Standard input is empty
stdout 
 1 3 5 2 4 3 5 10 10
1
3
5
2
4
3
5
10
10

1
3
2
4
3
10
10

3
4
3
10
1
10
2

Counts of 3 in array = 2

1
2
3
3
4
10
10

Removed!
https://ideone.com/7YdiQY
language:
C++ (gcc 8.3)
created:
11 years ago
visibility:
public

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