IntStack(存放int型值，带迭代器) p406

  1 #include "../require.h"
  2 #include <iostream>
  3 
  4 using namespace std;
  5 
  6 
  7 class IntStack
  8 {
  9     enum { ssize = 20 };
 10     int stack[ssize];
 11     int top;
 12 
 13 public:
 14     IntStack() : top(0) {}
 15     void push(int i)
 16     {
 17         require(top < ssize, "Too many push()es");
 18         stack[top++] = i; //int型元素，通过赋值运算符，直接存入IntStack栈内部的 int stack[]数组中
 19     }
 20 
 21     int pop()
 22     {
 23         require(top > 0, "Too many pop()s");
 24         return stack[--top];
 25     }
 26 
 27     class iterator;
 28     friend class iterator;
 29     
 30     class iterator
 31     {
 32         IntStack& intStack;
 33         int index;
 34 
 35     public:
 36         
 37         iterator(IntStack& is) : intStack(is), index(0) {}
 38 
 39         iterator(IntStack& is, bool) : intStack(is), index(is.top) {}
 40 
 41         // 返回迭代器当前位置的元素
 42         int current() const
 43         {
 44             return intStack.stack[index];
 45         }
 46         
 47         // ++i
 48         int operator++()
 49         {
 50             require(index < intStack.top, "iterator moved out of range");
 51             return intStack.stack[++index];
 52         }
 53  
 54         // i++
 55         int operator++(int)
 56         {
 57             require(index < intStack.top, "iterator moved out of range");
 58             return intStack.stack[index++];
 59         }
 60 
 61         // i += 2;
 62         iterator& operator+=(int amount)
 63         {
 64             require(index + amount < intStack.top, "IntStack::iterator::operator+=() tried to moved out of bounds");
 65             index += amount;
 66             return *this;
 67         }
 68 
 69         bool operator==(const iterator& rv) const
 70         {
 71             return index == rv.index;
 72         }
 73 
 74         bool operator!=(const iterator& rv) const
 75         {
 76             return index != rv.index;
 77         }
 78 
 79         friend ostream& operator<<(ostream& os, const iterator& it);
 80     };
 81 
 82     iterator begin()
 83     {
 84         return iterator(*this);
 85     }
 86 
 87     iterator end()
 88     {
 89         return iterator(*this, true);
 90     }
 91 };
 92 
 93 // 重载 << 运算符  -- 全局的
 94 ostream& operator<<(ostream& os, const IntStack::iterator& it)
 95 {
 96     return os << it.current();
 97 }
 98 
 99 
100 
101 int main()
102 {
103     IntStack stack;
104     for (int i = 0; i < 15; i++)
105     {
106         stack.push(i*3);
107     }
108 
109     //----------------------
110     cout << "Traverse the whole IntStack" << endl;
111     
112     IntStack::iterator it = stack.begin();
113     int n=0;
114     while (it != stack.end())
115     {
116         cout << n++ << ": " << it++ << endl;
117     }
118 
119 
120     //----------------------------------
121     cout << "Traverse a portion of the IntStack" << endl;
122 
123 
124     IntStack::iterator start = stack.begin(), end2 = stack.end();
125     start += 2; 
126     end2 += 5; //在此，程序退出
127 
128     cout << "start = " << start << endl;
129     cout << "end = " << end2 << endl;
130 
131     while (start != end2)
132     {
133         cout << start++ << endl;
134     }
135 
136     return 0;
137 };