如何防止在文件中添加空行？

Question

我正在創建一個文本文件，最后一行是“”

    private void lastRunDate()
    {
        String lastLine = readLastDate();
        String[] date = lastLine.Split('/');
        DateTime dt = new DateTime(Int32.Parse(date[2]), Int32.Parse(date[0]), Int32.Parse(date[1]));
        DateTime currentDT = DateTime.Now;

        argValue = 1;

        if ((dt.Month == currentDT.Month) && (argValue == 0))
        {
            MessageBox.Show("This application has already been run this month");
            this.Close();                
        }
    }


    private void AddRecordToFile()
    {
        DateTime now = DateTime.Now;
        prepareToEmail();
        string path = filepath;
        bool dirtyData = true;
        // This text is added only once to the file. 
        if (!File.Exists(path))
        {
            // Create a file to write to. 
            using (StreamWriter sw = File.CreateText(path))
            {
                sw.Write(now.ToShortDateString());                    
            }
            dirtyData = false;
        }

        if (dirtyData)
        {
            // This text is always added, making the file longer over time 
            // if it is not deleted. 
            using (StreamWriter sw = File.AppendText(path))
            {
                sw.Write(now.ToShortDateString());
            }
        }            
    }

    private String readLastDate()
    {
        using (StreamReader sr = new StreamReader(filepath))
        {
            // Initialize to null so we are not stuck in loop forever in case there is nothing in the file to read
            String line = null;
            do
            {
                line = sr.ReadLine();
                // Is this the end of the file?
                if (line == null)
                {
                    // Yes, so bail out of loop
                    return "01/01/1900"; // I had to put something
                }
                // Is the line empty?
                if (line == String.Empty)
                {
                    // Yes, so skip it
                    continue;
                }
                // Here you process the non-empty line
                return line;
            } while (true);
        }
    }

是我用來創建文件（或附加文件）的東西

現在是一個DateTime對象

我用您的（Karl）代碼創建了一個名為“ readLastDate（）”的方法

我得到了第一個約會。

Answer 1

我可能正在以務實和簡單的方式，但是跳過所有流內容並像這樣直接使用File類...

string newLine = "";
if (!isFirstLine)
    newLine = Environment.NewLine;

File.AppendAllText(
    filePath, 
    string.Format("{0}{1}", newLine, DateTime.Now.ToString()));

Answer 2

做這個：

sw.Write(now.ToShortDateString());

這是StreamWriter.WriteLine的MSDN文檔。

這是StreamWriter.Write的MSDN文檔。

更新：

繼續使用WriteLine ，但更改從文件讀取值的方式：

using (StreamReader sr = new StreamReader(path))
{
    // Initialize to null so we are not stuck in loop forever in case there is nothing in the file to read
    String line = null;

    do 
    {
        line = sr.ReadLine();

        // Is this the end of the file?
        if (line == null)
        {
            // Yes, so bail out of loop
            return;
        }

        // Is the line empty?
        if (line == String.Empty)
        {
            // Yes, so skip it
            continue;
        }

        // Here you process the non-empty line

    } while (true);
}

Answer 3

您是否嘗試過使用命令.Trimend（'\\ n'）？

http://msdn.microsoft.com/zh-CN/library/system.string.trimend.aspx

Answer 4

您可以使用sw.Write並預先添加換行符。 不幸的是，這將在文件開頭為空行。

Answer 5

如另一個答案所指出的，添加記錄應該是調用File.AppendAllText的簡單問題。 盡管我建議：

File.AppendAllText(filePath, DateTime.Now.ToString() + Environment.NewLine);

從文件中讀取最后一個日期也很容易：

string lastGoodLine = "01/01/1900";
using (StringReader sr = new StringReader(filePath))
{
    while (!sr.EndOfStream)
    {
        string line = sr.ReadLine();
        if (!string.IsNullOrEmpty(line))
            lastGoodLine = line;
    }
}
return lastGoodLine;