c++ std::rotate()的用法（一看就懂）

叁歲伎倆 2023-02-14 13:02 133阅读 0赞

*  **进行元素范围上的左旋转**  
    **用法**：**std::rotate( first\_element, n\_first( will be the first element after ratating ), last\_element )**

关于这个函数的具体的用法编写了如下代码，相信大家看完之后会有一个较好的认识：

**构造了两个函数，分别对于数组和字符串操作：**

//hmtian @ 2020/6/2 21:06
    
    #include<iostream>
    #include<string>
    #include<vector>
    #include<algorithm>
    #include<iterator>
    #include<cstdlib>
    #include<cstdio>
    #include<cassert>
    
    /****************************function**********************************/
    void rotate_order1(std::vector<int>& arr, int num)
    { 
            assert(num >= 0 && num < arr.size());
            std::rotate(arr.begin(),arr.begin() + num, arr.end());
    }
    
    void rotate_order2(std::string& str, int num)
    { 
            assert(num >= 0 && num < str.size());
            std::rotate(str.begin(),str.begin() + num, str.end());
    }
    /*********************************************************************/
    int main()
    { 
            std::vector<int> arr = { 1,2,3,4,5};
            std::string str = "abcde";
    
            for(int i = 0; i < arr.size(); i++)
            { 
                    rotate_order1(arr,i);
                    std::cout<<"[i]="<< i <<" ";
    
                    for(const auto& e : arr){ 
                            std::cout<< e ;}
                    std::cout<<"\n";
                    //std::cout<<" put the number of "<< i+1 << " element to the first position\n";
            }
            
            for(int i = 0; i < str.size(); i++)
            { 
                    rotate_order2(str,i);
                    std::cout<<"[i]="<< i <<" ";
    
                    for(const auto& e : str){ 
                            std::cout<< e ;}
                    std::cout<<"\n";
                    //std::cout<<" put the number of "<< i+1 << " element to the first position\n";
            }
    
            return 0;
    
    }

### 输出结果： ###

i = 0 时，意味着将第一个元素（arr.begin() + i）放在首位，之后 rotate后的数组或者字符串作为下一轮循环的输入，但是需要注意arr.begin()始终为1；现在应该就一目了然了。  
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