逐字输入字符串 [英] taking input of a string word by word

问题描述

我刚开始学习C ++。我只是玩弄它，遇到了一个问题，涉及接受一个字符串的字输入，每个字由空格分隔。我的意思是，假设我有

 名称place动物
  

作为输入。我想读第一个单词，做一些操作就可以了。然后读第二个字，做一些操作，然后读下一个字，等等。

我尝试用getline存储整个字符串，如下

：

 ＃include< iostream> 
 using namespace std; 
 int main（）
 {
 string t; 
 getline（cin，t）; 
 cout<< t; //只是为了确认输入是否正确读取
} 
  

操作每个单词并移动到下一个单词？

此外，因为我是新的，这可能是一个愚蠢的问题，地方，而不是使用使用命名空间std人们更喜欢写std ::
与一切。为什么？我认为他们做同样的事情。

解决方案

将该行放入一个字符串流中，并逐字提取单词：

  #include< iostream> 
 #include< sstream> 
 using namespace std; 
 
 int main（）
 {
 string t; 
 getline（cin，t）; 
 
 istringstream iss（t）; 
 string word; 
 while（iss>> word）{
 / * do stuff with word * / 
} 
} 
  

当然，你可以直接跳过getline部分并直接从 cin 逐字读取。 >

在这里，您可以阅读为什么使用命名空间std 视为不良做法

I just started learning C++. I was just playing around with it and came across a problem which involved taking input of a string word by word, each word separated by a whitespace. What I mean is, suppose I have

   name  place animal 

as the input. I want to read the first word, do some operations on it. Then read the second word, do some operations on that, and then read the next word, so on.

I tried storing the entire string at first with getline like this

    #include<iostream>
    using namespace std;
    int main()
    {
     string t;
     getline(cin,t);
     cout << t; //just to confirm the input is read correctly
    }

But then how do I perform operation on each word and move on to the next word?

Also, since I am new, this might seem a stupid question but while googling around about C++ I saw at many places, instead of using "using namespace std" people prefer to write "std::" with everything. Why's that? I think they do the same thing. Then why take the trouble of writing it again and again?

解决方案

Put the line in a stringstream and extract word by word back:

#include <iostream>
#include <sstream>
using namespace std;

int main()
{
    string t;
    getline(cin,t);

    istringstream iss(t);
    string word;
    while(iss >> word) {
        /* do stuff with word */
    }
}

Of course, you can just skip the getline part and read word by word from cin directly.

And here you can read why is using namespace std considered bad practice.

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