C ++从istream读取，直到换行符（但不是空格） [英] C++ read from istream until newline (but not whitespace)

问题描述

我有一个std :: istream指向矩阵数据，像：

  0.0 1.0 2.0 
 3.0 4.0 5.0 
  

现在，为了评估列数，我想有一些代码：

  std :: vector< double> vec; 
 double x; 
 while（（... something ...）&&（istream>> x））
 {
 vec.push_back（x）; 
} 
 //这里vec应包含0.0，1.0和2.0 
  

... ... ... ...部分在我读取2.0之后计算为false，istream在该点应该在3.0，以便下一个

  istream>> X; 
  

应设置x等于3.0。

你将如何实现这个结果？

解决方案

非常感谢您的帮助！ / div>

使用 查看 方法来检查下一个字符：

  while（（istream.peek（）！='\\\
'）& ;&（istream>> x））
  

I have a std::istream which refers to matrix data, something like:

0.0 1.0 2.0
3.0 4.0 5.0

Now, in order to assess the number of columns I would like to have some code like:

std::vector<double> vec;
double x;
while( (...something...) && (istream >> x) )
{
    vec.push_back(x); 
}
//Here vec should contain 0.0, 1.0 and 2.0

where the ...something... part evaluates to false after I read 2.0 and istream at the point should be at 3.0 so that the next

istream >> x;

should set x equal to 3.0.

How would you achieve this result? I guess that the while condition

Thank you very much in advance for your help!

解决方案

Use the peek method to check the next character:

while ((istream.peek()!='\n') && (istream>>x))

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