【C++ Primer】【学习笔记】【第九章】顺序容器之：迭代器和迭代器范围

小灰灰 2022-08-07 03:54 325阅读 0赞

**一、所有标准库容器都可以使用的迭代器运算**

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     <span style="background-color:inherit"><strong>所有标准库容器都支持的迭代器运算</strong></span> 
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      返回迭代器iter所指向的元素的引用 
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      iter-&gt;mem 
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      获取指定元素中名为mem的成员，等效于(*iter).mem 
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      ++iter 
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      iter++ 
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      --iter 
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      iter-- 
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      使iter指向容器里的前一个元素 
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      iter1 == iter2 
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      iter1 != iter2 
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      当两个迭代器都指向同一个容器的同一个元素或者同一个容器的超出末端的下一个位置时，两个迭代器相等；否则，两个迭代器不相等。 
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**二、vector和deque类型容器支持的迭代器运算**

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     <span style="background-color:inherit"><strong>vector和deque标准库容器支持的迭代器运算</strong></span> 
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     <span style="font-family:微软雅黑; font-size:14px">使iter指向容器里的前面或后面的第n个元素</span> 
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      iter1 += iter2 
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      iter1 -= iter2 
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      iter1 - iter2 
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      迭代器的复合赋值运算以及减法运算 
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      &gt;, &gt;=, &lt;, &lt;= 
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**习题9.9：将list容器中的元素进行反向输出**

#include <iostream>
    #include <string>
    #include <utility>
    #include <vector>
    #include <list>
    #include <map>
    using namespace std;
    
    int main()
    {
        int ia[5] = {0, 1, 2, 3, 4};
        int num = sizeof(ia) / sizeof(int);
    
        list<int> ilist(ia, ia + num);
       
        for (list<int>::iterator iter = ilist.end(); iter != ilist.begin();)
        {
            printf("%d\n", *(--iter));
        }
    
        return 0;
    }

[chapter9]$ ./a.out
    4
    3
    2
    1
    0

**习题9.12：使用迭代器查找一个元素在容器中是否存在**

#include <iostream> 
    #include <string>
    #include <utility>
    #include <vector>
    #include <list>
    #include <map>
    using namespace std;
    
    // find ival between beg and end
    // if find, return true; if not find, return false;
    bool find_int(vector<int>::iterator beg, vector<int>::iterator end, int ival)
    {
        while (beg != end)
        {
            if (*beg++ == ival) return true;
        }
            
        return false;
    }
    
    int main()
    {
        int ia[5] = {0, 1, 2, 3, 4};
        int num = sizeof(ia) / sizeof(int);
    
        vector<int> ivec(ia, ia + num);
        
        for (int i = 0; i < 10; i++)
        {
            bool bool_val = find_int(ivec.begin(), ivec.end(), i);
            printf("The result of find %d is: %s.\n", i, (bool_val == true) ? "true" : "false");
        }
    
        return 0;
    }

[chapter9]$ ./a.out 
    The result of find 0 is: true.
    The result of find 1 is: true.
    The result of find 2 is: true.
    The result of find 3 is: true.
    The result of find 4 is: true.
    The result of find 5 is: false.
    The result of find 6 is: false.
    The result of find 7 is: false.
    The result of find 8 is: false.
    The result of find 9 is: false.