C ++使用stringstream后<<作为参数 [英] C++ Using stringstream after << as parameter

问题描述

是否可以编写一个接受字符串流的方法，并使其看起来像这样：

  void method（string str）
 void printStringStream（StringStream& ss）
 {
 method（ss.str 
} 
  

可以像这样调用

  stringstream var; 
 printStringStream（var<<Text<< intVar<<More text<< floatvar）; 
  

我查找了<运算符，它看起来像返回一个 ostream& 对象，但我可能读取 此 错误或只是无法正确实施。 >

真正我想要的是一个干净的方式，将字符串连接在一起并传递给函数。我能找到的最干净的事情是一个stringstream对象，但仍然有很多不足之处。

注意：

c> c ++ 11 答案，因为我在Visual Studio 2010上运行（根据我的意愿，但仍然）

Boost 所以要坚持下去。

我不会反对一个自定义方法，只要它清理这个混乱。

编辑：

PiotrNycz语法我实现了我写这样的代码的目标，

  try {
 
 // code 
 
} catch（exception e）
 {
 printStringStream（stringstream（）<<发生异常。\\\

<<Error：<< e.message 
<<\\\
如果此问题仍然存在，请联系<< contactInfo 
< \\ n对不便，我们深表歉意）; 
} 
  

这是我所希望的那样干净，可读。

希望这有助于其他人清理写信息。

解决方案

，带我一分钟。由于运算符<< 是为所有 ostream类型重载的自由函数，因此不会返回 std :: stringstream ，它像你说的那样返回 std :: ostream 。

  void printStringStream（std :: ostream& ss）
  

ostream 没有 .str（）成员，但他们有一种将整个流复制到另一个流的奇妙方式：

  std :: cout< ss.rdbuf（）; 
 

这是一个指向完整代码的链接，显示它编译和运行 http://ideone.com/DgL5V

EDIT

如果你真的需要一个字符串的函数，我可以想到几个解决方案：

首先， p>

  stringstream var; 
 var<< Text<< intVar<< More text<<< floatvar; 
 printStringStream（var）; 
  

其次：将流复制到字符串（可能的性能问题）

  void printStringStream（ostream& t）
 {
 std :: stringstream ss; 
 ss<< t.rdbuf（）; 
 method（ss.str（））; 
} 
  

第三步：使另一个函数接受流

Is it possible to write a method that takes a stringstream and have it look something like this,

void method(string str)
void printStringStream( StringStream& ss)
{
    method(ss.str());
}

And can be called like this

stringstream var;
printStringStream( var << "Text" << intVar << "More text"<<floatvar);

I looked up the << operator and it looks like it returns a ostream& object but I'm probably reading this wrong or just not implementing it right.

Really all I want is a clean way to concatenate stuff together as a string and pass it to a function. The cleanest thing I could find was a stringstream object but that still leaves much to be desired.

Notes:

I can't use much of c++11 answers because I'm running on Visual Studio 2010 (against my will, but still)

I have access to Boost so go nuts with that.

I wouldn't be against a custom method as long as it cleans up this mess.

Edit:

With @Mooing Duck's answer mixed with @PiotrNycz syntax I achieved my goal of written code like this,

try{

    //code

}catch(exception e)
{   
    printStringStream( stringstream() << "An exception has occurred.\n"
                            <<"    Error: " << e.message 
                            <<"\n If this persists please contact "<< contactInfo
                            <<"\n Sorry for the inconvenience");
}

This is as clean and readable as I could have hoped for.

Hopefully this helps others clean up writing messages.

解决方案

Ah, took me a minute. Since operator<< is a free function overloaded for all ostream types, it doesn't return a std::stringstream, it returns a std::ostream like you say.

void printStringStream(std::ostream& ss)

Now clearly, general ostreams don't have a .str() member, but they do have a magic way to copy one entire stream to another:

std::cout << ss.rdbuf();

Here's a link to the full code showing that it compiles and runs fine http://ideone.com/DgL5V

EDIT

If you really need a string in the function, I can think of a few solutions:

First, do the streaming seperately:

stringstream var;
var << "Text" << intVar << "More text"<<floatvar;
printStringStream(var);

Second: copy the stream to a string (possible performance issue)

void printStringStream( ostream& t)
{
    std::stringstream ss;
    ss << t.rdbuf();
    method(ss.str());
}

Third: make the other function take a stream too

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