在C＃中读取文本文件 [英] Reading a text file in C#

问题描述

我正在使用下面给出的代码在C＃中读取文本文件，理想情况下这应该逐个读取每一行，但问题是在阅读时跳过每个备用行，我无法理解问题是什么是。请对任何解决方案有任何帮助。

  string  fileName = < span class =code-string> @  C：\NewTextDoc.txt; 
 
  string  str =  string  .Empty; 
 
  if （File.Exists（fileName））
 {
 StreamReader sr =  new  StreamReader（fileName）; 
  String 行; 
 
  while （sr.ReadLine（）！=  null ）
 {
 line = sr.ReadLine（）; 
  if （line.Trim（）！=  string  .Empty）
 { 
s = line.substring（ 1 ， 4 ）; 
} 
} 
} 
  else  
 {
s =  文件不存在; 
} 
  return  s; 
 

解决方案

你正在做什么

  while （sr.ReadLine（）！=  null ）

消耗一条线，然后你再次 line = sr.ReadLine（）; ，消耗另一条线，但只第二个读数存储在 sr 。



您可以将其更改为此;

  while （（line = sr.ReadLine（））！=  null ）
 {
  if （line.Trim（）！=  string  .Empty）
 {
s = line.substring（ 1 ， 4 ）; 
} 
} 

或者只是使用 FileInfo.ReadAllLines 除非你的文件非常庞大。



希望这会有所帮助，

Fredrik

< blockquote>首先你做的是：

  while （sr.ReadLine（）！=  null ）

文件中的指针移动到下一行。然后你做

 line = sr.ReadLine（）; 

所以指针再次移动。这会带给你一段时间...

当你认为你读到的文件减半时宣布。



你需要阅读文件逐行？

你可以根据 MSDN [ ^ ]

您实际上正在调用 StreamReader.Readline 方法两次 （都在而条件和 line = sr.ReadLine; 语句中，但只使用其中一个返回价值）。

如文档 [ ^ ]代码示例，您可以使用 StreamReader.Peek 方法来检查文件结束条件：

 而（sr.Peek（）>  =  0 ）
 {
 line = sr.ReadLine（）; 
  //   ..  
} 
 

I was reading a text file in C# by code as given below , ideally this should read each and every line one by one but the problem is every alternate line is skipped while reading , I'm not able to understand what the problem is . Please can any help with any solution.

string fileName = @"C:\NewTextDoc.txt";

string str = string.Empty;

if (File.Exists(fileName))
{
    StreamReader sr = new StreamReader(fileName);
    String line;

    while (sr.ReadLine() != null)
    {
        line = sr.ReadLine();
        if (line.Trim() != string.Empty)
        {
           s = line.substring(1,4) ;
        }
    }
}
else
{
    s = "File does not exists";
}
return s;

解决方案

You're doing

while(sr.ReadLine() != null)

That consumes a line, then you're doing line = sr.ReadLine(); again, that consumes another line, but only the second read is stored in sr.

You could change it to this;

while ((line = sr.ReadLine()) != null)
{
  if (line.Trim() != string.Empty)
  {
    s = line.substring(1,4) ;
  }
}

Or maybe just use FileInfo.ReadAllLines unless your file is absolutely massive in size.

Hope this helps,
Fredrik

first you do in the while:

while (sr.ReadLine() != null)

The pointer in the file moves to the next line. And then you do

line = sr.ReadLine();

so the pointer is moved again. which brings you to the while...
That declares while you think you read halve the file.

do you need to read the file line by line?
You can read it very simple according to MSDN[^]

You are actually calling StreamReader.Readline method twice (both in the while condition and in the line = sr.ReadLine; statement, but using only one of the return values).
As in the documentation[^] code sample, you may use StreamReader.Peek method to check for the End Of File condition:

while (sr.Peek() >= 0)
{
   line = sr.ReadLine();
   //..
}

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