如何使用 StreamReader 将分割线添加到字典中？

Question

我正在尝试使用 StreamReader 读取 .txt 文件，拆分行并将它们添加到字典中，但是当我调试它时，它不起作用，因为第一行是空的，而且它没有继续.我如何定义字符串 fullLine 使其工作？

        StreamReader sr = new StreamReader(@"N:\Desktop\krew.txt");
        StreamWriter sw = new StreamWriter(@"N:\Desktop\newKrew.txt");
        Dictionary<string, string> dict = new Dictionary<string, string>();
        string fullLine = "";


        while (fullLine != null)
        {
            fullLine = sr.ReadLine();
            string[] wholeLine = fullLine.Split('\t');
            dict.Add(wholeLine[0], wholeLine[1]);

Answer 1

您可以尝试 Linq 并让 .Net 打开（和 Dispose）Streams，Readers 为您服务

 using System.Linq;

 ...

 Dictionary<string, string> dict = File
   .ReadLines(@"N:\Desktop\krew.txt")
   .Where(line => !string.IsNullOrEmpty(line)) // to be on the safe side
   .Select(line => line.Split('\t'))
   .ToDictionary(items => items[0], items => items[1]);

添加到现有词典中：

 var lines = File
   .ReadLines(@"N:\Desktop\krew.txt")
   .Where(line => !string.IsNullOrEmpty(line))
   .Select(line => line.Split('\t'));

 foreach (var wholeLine in lines)
   dict.Add(wholeLine[0], wholeLine[1]);

如果您坚持StreamReader，您可以实现一个简单的for循环：

// Do not forget to Dispose it
using (StreamReader sr = new StreamReader(@"N:\Desktop\krew.txt")) {
  // if fullLine == null, sr is at the end and can't read any more lines
  for (string fullLine = sr.ReadLine(); fullLine != null; fullLine = sr.ReadLine()) {
    string[] wholeLine = fullLine.Split('\t');
    dict.Add(wholeLine[0], wholeLine[1]);
  } 
}

Answer 2

你最好这样写循环：

while (true)
{
    string fullLine = sr.ReadLine();

    if (fullLine == null)
        break;

    string[] wholeLine = fullLine.Split('\t');
    dict.Add(wholeLine[0], wholeLine[1]);
    ...

正如您现在编写的循环，fullLine 将在文件末尾变为 null，然后 fullLine.Split('\t'); 将抛出 NullReferenceException.

我怀疑你所说的 first line is null and it doesn't go further 就是这个意思。它实际上不可能是导致问题的 first 行，因为您将 fullLine 初始化为“”，但我认为这是根本问题。

Answer 3

在 while 循环中使用 .Peek() 方法读取文件末尾。它应该通过你的第一行是空的。

Null is no the same thing as ""

Peek() will check for the next character and it the line is blank it will return "".

If you have lines on line 2 through X then the blank lines are not null, therefore .Peek() will return -1. Check out the documentation on it.

.Peek() https://docs.microsoft.com/en-us/dotnet/api/system.io.streamreader.peek?view=netframework-4.8

//Doing it in a Using statement to properly dispose of the StreamReader
using (StreamReader sr = new StreamReader(path)) 
            {

                while (sr.Peek() > -1) 
                {
                    Console.WriteLine(sr.ReadLine());
                }
            }

Answer 4

像这样更改您的代码

while ((fullLine = sr.ReadLine()) != null)
        {
            string[] wholeLine = fullLine.Split('\t');
            dict.Add(wholeLine[0], wholeLine[1]);
        }

Answer 5

尝试使用波纹管。这会将行变量设置为文件中的每一行

    StreamReader sr = new StreamReader(@"N:\Desktop\krew.txt");
    Dictionary<string, string> dict = new Dictionary<string, string>();
    string line;

    while ((line = sr.ReadLine()) != null)
    {
        string[] wholeLine = line.Split('\t');
        dict.Add(wholeLine[0], wholeLine[1]);
    }

Answer 6

如果您不完全依赖有使用 StreamReader..

    string[] read = File.ReadAllLines(filepath);
    for (int i = 0; i < read.Length; i++)
    {
        if (string.IsNullOrEmpty(read[i])
            continue;
        string[] lineArray = read[i].Split(new [] {" "}, StringSplitOptions.None);
        dict.Add(lineArray[0], lineArray[1]);
    }

如何使用 StreamReader 将分割线添加到字典中？

How do I use StreamReader to add split lines to a dictionary?

c#

split

streamreader