Reading and writing of C ＃ file

Reading documents

Use the form of file stream ,StreamRead Medium ReadLine Method , It should be noted that relative paths can also be selected

            //  Create a  StreamReader  To read the file  
            // using  Statements can also be closed  StreamReader
            using (StreamReader sr = new StreamReader("c:/jamaica.txt"))
            {
                string line;
               
                //  Read from file and display lines , To the end of the file  
                while ((line = sr.ReadLine()) != null)
                {
                    Console.WriteLine(line);
                }
            }

Writing documents

StreamWriter Medium WriteLine Method , It should be noted that relative paths can also be selected

    using (StreamWriter sw = new StreamWriter(System.Windows.Forms.Application.StartupPath + "\\access_path.txt"))
        {
            //sw.Write(" Data to be saved to a file ");// Write a line without newline 
            sw.WriteLine(" Data to be saved to a file ");// Writes a line terminator to a text string or stream 
            sw.Flush();
         }

Judge whether the file exists , create a file

Sometimes when reading a file, you need to judge whether the file exists ：System.Windows.Forms.Application.StartupPath The path for the software to run . Note that when adding the file name, add “\”

if(File.Exists(System.Windows.Forms.Application.StartupPath+"\\access_path.txt"))
        {
            StreamReader sr = new StreamReader(System.Windows.Forms.Application.StartupPath + "\\access_path.txt", Encoding.Default);
            string content = sr.ReadLine();// Only one line of data in the file is read here 
            sr.Close();
        }
        else
        {
            using (File.Create(System.Windows.Forms.Application.StartupPath + "\\access_path.txt"))
            {
                // Actions after file creation    May be empty 
            }
        }        

Delete file

File.Delete(filePath);