[day_020419] inverted string

Inverted string

Title source

Cattle from ： Inverted string

Title Description

Invert the words of a sentence , Punctuation is not inverted . such as I like beijing. After passing through the function, it becomes ：beijing. like I

Input description

Each test input contains 1 Test cases ： I like beijing. The length of the input case shall not exceed 100

Output description

Output the inverted string in turn , Split by space

Example 1

Input

I like beijing.

Output

beijing. like I

Thought analysis

• First put the whole sentence upside down , Then reverse word by word
• The outer loop represents the entire string , The inner loop is used to reverse the interval separated by each space , That is, a word
• The inner loop condition is that the current iterator does not point to spaces , And not at the end of the string
• Because inversion is used reverse function , So iterators are used to traverse the string

Code display

#include<iostream>
#include<algorithm>
#include<string>

using namespace std;
int main()
{
    
    string s;
    getline(cin,s);
    reverse(s.begin(),s.end());
    auto start=s.begin();
    while(start!=s.end())
    {
    
        auto end=start;
        // Notice that a space is a character , Use ' ' Single quotation marks 
        while(*end!=' '&&end!=s.end())
        {
    
            end++;
        }
        
        // In both cases reverse, So the reverse Let me write it first 
        reverse(start,end);
        
        // Here, if the judgment condition cannot be written if(*end=' '),
        // because end The value at the end of the string is NULL, Dereference will cause segment errors 
        if(end!=s.end())
        {
    
            start=end+1;
        }
        else
        {
    
            start=s.end();
        }
    }
    cout<<s;
    return 0;
}