Question

我试图逐行读取文本文件，并从多行创建一行，直到读入的行末尾有\ r \ n。我的数据如下：

BusID|Comment1|Text\r\n
1010|"Cuautla, Inc. d/b/a 3 Margaritas VIII\n
State Lic. #40428210000   City Lic.#4042821P\n
9/26/14      9/14/14 - 9/13/15    $175.00\n
9/20/00    9/14/00 - 9/13/01    $575.00 New License"\r\n
1020|"7-Eleven Inc., dba 7-Eleven Store #20638\n
State Lic. #24111110126; City Lic. #2411111126P\n
SEND ISSUED LICENSES TO DALLAS, TX\r\n

我希望数据看起来像这样：

BusID|Comment1|Text\r\n
1010|"Cuautla, Inc. d/b/a 3 Margaritas VIII State Lic. #40428210000   City Lic.#4042821P 9/26/14      9/14/14 - 9/13/15    $175.00 9/20/00    9/14/00 - 9/13/01    $575.00 New License"\r\n
1020|"7-Eleven Inc., dba 7-Eleven Store #20638 State Lic. #24111110126; City Lic. #2411111126P SEND ISSUED LICENSES TO DALLAS, TX\r\n

我的代码是这样的：

FileStream fsFileStream = new FileStream(strInputFileName, FileMode.Open, 
FileAccess.Read, FileShare.ReadWrite);

using (StreamReader srStreamRdr = new StreamReader(fsFileStream))
{
    while ((strDataLine = srStreamRdr.ReadLine()) != null && !blnEndOfFile)
    {
        //code evaluation here
    }

我试过了：

if (strDataLine.EndsWith(Environment.NewLine))
{
    blnEndOfLine = true;
}

和

if (strDataLine.Contains(Environment.NewLine))
{
    blnEndOfLine = true;
}

这些在字符串变量的末尾看不到任何内容。有没有办法让我告诉真正的行尾，以便我可以将这些行组合成一行？我应该以不同的方式阅读文件吗？

Answer 1

如果您发布的内容与文件中的内容完全相同。这意味着\ r \ n确实是写的，你可以使用以下内容来取消它们：

strDataLine.Replace("\\r", "\r").Replace("\\n", "\n");

这将确保您现在可以使用Environment.NewLine进行比较，如下所示：

if (strDataLine.Replace("\\r", "\r").Replace("\\n", "\n").EndsWith(Environment.NewLine))
{
    blnEndOfLine = true;
}

Answer 2

您不能使用StringReader的ReadLine方法，因为每种类型的换行符都是如此。从输入中删除\r\n和\n，读取器返回一行，您永远不会知道删除的字符是\ r \ n还是只是\ n

如果文件不是很大，那么你可以尝试将所有内容加载到内存中并将自己分成单独的行

// Load everything in memory
string fileData = File.ReadAllText(@"D:\temp\myData.txt");

// Split on the \r\n (I don't use Environment.NewLine because it 
// respects the OS conventions and this could be wrong in this context
string[] lines = fileData.Split(new string[] { "\r\n"}, StringSplitOptions.RemoveEmptyEntries);

// Now replace the remaining \n with a space 
lines = lines.Select(x => x.Replace("\n", " ")).ToArray();

foreach(string s in lines)
   Console.WriteLine(s);

修改
如果您的文件非常大（就像您说的3.5GB），那么您无法在内存中加载所有内容，但需要在块中处理它。幸运的是，StreamReader提供了一个名为ReadBlock的方法，它允许我们实现像这样的代码

// Where we store the lines loaded from file List<string> lines = new List<string>(); // Read a block of 10MB char[] buffer = new char[1024 * 1024 * 10]; bool lastBlock = false; string leftOver = string.Empty; // Start the streamreader using (StreamReader reader = new StreamReader(@"D:\temp\localtext.txt")) { // We exit when the last block is reached while (!lastBlock) { // Read 10MB int loaded = reader.ReadBlock(buffer, 0, buffer.Length); // Exit if we have no more blocks to read (EOF) if(loaded == 0) break; // if we get less bytes than the block size then // we are on the last block lastBlock = (loaded != buffer.Length); // Create the string from the buffer string temp = new string(buffer, 0, loaded); // prepare the working string adding the remainder from the // previous loop string current = leftOver + temp; // Search the last \r\n int lastNewLinePos = temp.LastIndexOf("\r\n"); if (lastNewLinePos > -1) { // Prepare the working string current = leftOver + temp.Substring(0, lastNewLinePos + 2); // Save the incomplete parts for the next loop leftOver = temp.Substring(lastNewLinePos + 2); } // Process the lines AddLines(current, lines); } } void AddLines(string current, List<string> lines) { var splitted = current.Split(new string[] { "\r\n" }, StringSplitOptions.RemoveEmptyEntries); lines.AddRange(splitted.Select(x => x.Replace("\n", " ")).ToList()); }

此代码假定您的文件始终以\ r \ n结尾，并且您始终在10MB文本块中获得\ r \ n。您的实际数据需要进行更多测试。

Answer 3

您可以通过调用File.ReadAllText(path)来阅读所有文本，并按以下方式解析：

            string input =  File.ReadAllText(your_file_path);
            string output = string.Empty;
            input.Split(new[] { Environment.NewLine } , StringSplitOptions.RemoveEmptyEntries).
                Skip(1).ToList().
                ForEach(x =>
                {
                    output += x.EndsWith("\\r\\n") ? x + Environment.NewLine 
                                                   : x.Replace("\\n"," ");
                });

如何判断StreamReader.Readline（）末尾是否有environment.newline

3 个答案: