用下划线替换空格 [英] Replace space with an underscore

问题描述

到目前为止，我已经有了。

  string space2underscore（string text）
 {
 for（int i = 0; i  {
 if（text [i] ==''）
 text [i] ='_'; 
} 
 return text; 
} 
  

大多数情况下，如果我做的像这样， / p>

  string word =hello stackoverflow; 
 word = space2underscore（word）; 
 cout<<字; 
  

这将输出hello_stackoverflow，这正是我想要的。

但是，如果我要做像

  
 cin>>字; 
 word = space2underscore（word）; 
 cout<<字; 
  

我会得到第一个单词hello。

有人知道这个问题吗？

解决方案

问题是 cin >> word 只读取第一个单词。如果您想要像整个操作一样操作，您应该使用 std :: getline 。

例如：

  std :: string s; 
 std :: getline（std :: cin，s）; 
 s = space2underscore（s）; 
 std :: cout<< s<< std :: endl; 
  

此外，您可能要检查您实际上是否能够读取行。你可以这样做：

  std :: string s; 
 if（std :: getline（std :: cin，s））{
 s = space2underscore（s）; 
 std :: cout<< s<< std :: endl; 
} 
  

---

注意，你可能以更清晰的方式写你的函数。我个人会这样写：

  std :: string space2underscore（std :: string text）{
 （std :: string :: iterator it = text.begin（）; it！= text.end（）; ++ it）{
 if（* it ==''）{
 * it ='_'; 
} 
} 
 return text; 
} 
  

或者对于奖励积分，使用 std :: transform ！

编辑：
如果你碰巧足够幸运能够使用c ++ 0x功能（我知道这是一个大if），你可以使用lambdas和 std :: transform ，这将产生一些非常简单的代码：

  std :: string s = hello stackoverflow; 
 std :: transform（s.begin（），s.end（），s.begin（），[]（char ch）{
 return ch ==''？'_'：ch ; 
}）; 
 std :: cout<< s<< std :: endl; 
  

I am trying to write something that will replace all the spaces in a string with an underscore.

What I have so far.

string space2underscore(string text)
{
    for(int i = 0; i < text.length(); i++)
    {
        if(text[i] == ' ')
            text[i] = '_';
    }
    return text;
}

For the most part this would work, if I was doing something like.

string word = "hello stackoverflow";
word = space2underscore(word);
cout << word;

That would output "hello_stackoverflow", which is just what I want.

However if I was to do something like

string word;
cin >> word;
word = space2underscore(word);
cout << word;

I would just get the first word, "hello".

Does anybody know a fix for this?

解决方案

The problem is that cin >> word is only going to read in the first word. If you want to operate on a whole like at a time, you should use std::getline.

For example:

std::string s;
std::getline(std::cin, s);
s = space2underscore(s);
std::cout << s << std::endl;

Also, you may want to check that you actually were able to read a line. You can do that like this:

std::string s;
if(std::getline(std::cin, s)) {
    s = space2underscore(s);
    std::cout << s << std::endl;
}

---

Finally, as a side note, you could probably write your function in a cleaner way. Personally I would write it like this:

std::string space2underscore(std::string text) {
    for(std::string::iterator it = text.begin(); it != text.end(); ++it) {
        if(*it == ' ') {
            *it = '_';
        }
    }
    return text;
}

Or for bonus points, use std::transform!

EDIT: If you happen to be lucky enough to be able to use c++0x features (and I know that's a big if) you could use lambdas and std::transform, which results in some very simple code:

std::string s = "hello stackoverflow";
std::transform(s.begin(), s.end(), s.begin(), [](char ch) {
    return ch == ' ' ? '_' : ch;
});
std::cout << s << std::endl;

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