simple C++ iterator

一个简单的迭代器的实现。

  1 #include <iostream>
  2 #include <cassert>
  3 using namespace std;
  4 
  5 
  6 template <typename T>
  7 class MyVector
  8 {
  9 public:
 10     class MyIterator
 11     {// override * ++ -- = [] + == !=
 12 
 13     public:
 14         MyIterator():iterHandle(0),iterIndex(0){};
 15         //MyIterator(T* ptr){
 16         //    iterHandle = ptr;
 17         //    iterIndex = 0;
 18         //};
 19         ~MyIterator(){};
 20 
 21         T &operator * ()
 22         {
 23             return *iterHandle;
 24         }
 25 
 26         MyIterator& operator++()
 27         {
 28             iterHandle = iterHandle+1;
 29             iterIndex = iterIndex+1;
 30             return *this;
 31         }
 32 
 33         MyIterator& operator--()
 34         {
 35             iterHandle = iterHandle-1;
 36             iterIndex = iterIndex-1;
 37             return *this;
 38         }
 39 
 40         MyIterator& operator=(T * otherIt)
 41         {
 42             iterHandle = otherIt;
 43             return *this;
 44         }
 45 
 46         MyIterator& operator +(int n)
 47         {
 48             iterHandle += n;
 49             iterIndex += n;
 50             return *this;
 51         }
 52         int index()
 53         {
 54             return iterIndex;
 55         }
 56         bool operator==(T * otherIt)
 57         {
 58             return iterHandle==otherIt;
 59         }
 60         bool operator!=(T * otherIt)
 61         {
 62             return iterHandle!=otherIt;
 63         }
 64 
 65     private:
 66         T * iterHandle;
 67         int iterIndex;
 68     };
 69 
 70     MyVector(){
 71         mySize = 1;
 72         myData = malloc(sizeof(T));
 73     };
 74     MyVector(int sizeT){
 75         mySize = sizeT;
 76         int temp = sizeof(T)*sizeT;
 77         myData = (T*)malloc(temp);
 78         for(int i=0;i<sizeT;i++)
 79         {
 80             myData[i] = 0;
 81         }
 82 
 83     };
 84     //MyVector(int sizeT);
 85     ~MyVector(){
 86         free(myData);
 87         myData = NULL;
 88         mySize = 0;
 89     };
 90 
 91     T &operator [](int n)
 92     {
 93         return myData[n];
 94     }
 95     T *begin()
 96     {
 97         return (myData);
 98     }
 99     T *end()
100     {
101         return (myData+mySize);
102     }
103     int size()
104     {
105         return mySize;
106     }
107 
108     void clear()
109     {
110         free(myData);
111         myData = NULL;
112         mySize = 0;
113     }
114     void push_back(const T tempVlue)
115     {
116         T * handleTemp;
117         mySize +=1;
118         handleTemp = (T*)malloc(sizeof(T)*(mySize));
119         for(int i=0;i<mySize-1;i++)
120         {
121             handleTemp[i] = myData[i];
122         }
123         handleTemp[mySize-1] = tempVlue;
124         free(myData);
125         myData = handleTemp;
126         handleTemp = NULL;
127     }
128 
129 private:
130     T* myData;
131     int mySize;
132 
133 };

MyVector.h

 1 #include "MyVector.h"
 2 #include <vector>
 3 #include <iterator>
 4 #include <iostream>
 5 #include <algorithm>
 6 using namespace std;
 7 
 8 
 9 void printT(float x)
10 {
11     cout << x << endl;
12 }
13 int main()
14 {
15     vector<int> vec(3);
16     fill(vec.begin(),vec.end(),3);
17     vector<int>::iterator iter = vec.begin();
18 
19     for(;iter != vec.end();iter++)
20     {
21         cout<<*iter<<endl;
22     }
23 
24     cout<<"
"<<endl;
25 
26     MyVector<float> vec2(3);
27     MyVector<float>::MyIterator iter2;
28     vec2[0] = 2;
29     vec2[1] = 3;
30     vec2[2] = 4;
31 
32     iter2=vec2.begin();
33     for(;iter2!=vec2.end();++iter2)
34     {
35         cout<<*(iter2)<<endl;
36     }
37     for_each(vec2.begin(), vec2.end(),printT);
38     //auto f = [](float x) {cout << x <<endl;};
39     //for_each(vec2.begin(), vec2.end(), f);
40     //int a = 1;
41     //int b = 2;
42 //
43     //auto f = [a,b](int c){return a+b+c;};
44     //test(f);
45     return 0;
46 }

main.cpp

输出结果。

 1 3
 2 3
 3 3
 4 
 5 
 6 2
 7 3
 8 4
 9 2
10 3
11 4
12 
13 Process finished with exit code 0

result

有两个问题：

第一个，不支持lambda表达式，c++完全支持，gcc版本是4.9.2,clion自带cmake版本是3.7.2.

第二个是类型转换的疑惑，begin和end都赋值给了迭代器，有疑惑的是什么时候进行了类型转换。经过大神提示，我自己写的重载operate=自己都没注意到-。-。囧！