C#文件操作、读取文件、Debug/Trace类用法

        public static bool Exists(string? path)
        {
            try
            {
                // 可以将 string? 改成 string
                if (path == null)
                    return false;
                if (path.Length == 0)
                    return false;

                path = Path.GetFullPath(path);

                // After nORMalizing, check whether path ends in directory separator.
                // Otherwise, FillAttributeInfo removes it and we may return a false positive.
                // GetFullPath should never return null
                Debug.Assert(path != null, "File.Exists: GetFullPath returned null");
                if (path.Length > 0 && PathInternal.IsDirectorySeparator(path[^1]))
                {
                    return false;
                }

                return InternalExists(path);
            }
            catch (ArgumentException) { }
            catch (NotSupportedException) { } // Security can throw this on ":"
            catch (SecurityException) { }
            catch (IOException) { }
            catch (UnauthorizedAccessException) { }

            return false;
        }

Path.GetFullPath(path)

        public static byte[] ReadAllBytes(string path)
        {
            // bufferSize == 1 used to avoid unnecessary buffer in FileStream
            using (FileStream fs = new FileStream(path, FileMode.Open, FileAccess.Read, FileShare.Read, bufferSize: 1))
            {
                long fileLength = fs.Length;
                if (fileLength > int.MaxValue)
                    throw new IOException(SR.IO_FileTooLong2GB);

                int index = 0;
                int count = (int)fileLength;
                byte[] bytes = new byte[count];
                while (count > 0)
                {
                    int n = fs.Read(bytes, index, count);
                    if (n == 0)
                        throw Error.GetEndOfFile();
                    index += n;
                    count -= n;
                }
                return bytes;
            }
        }

        FileStream fs = new FileStream(path, 
                                       FileMode.Open, 
                                       FileAccess.Read, 
                                       FileShare.Read, 
                                       bufferSize: 1)

        private static byte[] InternalReadAllBytes(String path, bool checkHost)
        {
            byte[] bytes;
            // 此 FileStream 的构造函数不是 public ，开发者不能使用
            using(FileStream fs = new FileStream(path, FileMode.Open, FileAccess.Read, FileShare.Read, 
                FileStream.DefaultBufferSize, FileOptions.None, Path.GetFileName(path), false, false, checkHost)) {
                // Do a blocking read
                int index = 0;
                long fileLength = fs.Length;
                if (fileLength > Int32.MaxValue)
                    throw new IOException(Environment.GetResourceString("IO.IO_FileTooLong2GB"));
                int count = (int) fileLength;
                bytes = new byte[count];
                while(count > 0) {
                    int n = fs.Read(bytes, index, count);
                    if (n == 0)
                        __Error.EndOfFile();
                    index += n;
                    count -= n;
                }
            }
            return bytes;
        }

internal const int DefaultBufferSize = 4096;

ConsoleTraceListener console = new ConsoleTraceListener();
Trace.Listeners.Add(console);

        Trace.Listeners.Add(new TextWriterTraceListener(Console.Out));
        Debug.WriteLine("aa");

TraceListener listener = new DelimitedListTraceListener(@"C:\debugfile.txt");

        // Add listener.
        Debug.Listeners.Add(listener);

        // Write and flush.
        Debug.WriteLine("Welcome");

ConsoleTraceListener console=...
...Listeners.Add(console);

// 等效于
var console = new TextWriterTraceListener(Console.Out)

        // 1.
        Debug.WriteLine("One");

        // Indent and then unindent after writing.
        Debug.Indent();
        Debug.WriteLine("Two");
        Debug.WriteLine("Three");
        Debug.Unindent();

        // End.
        Debug.WriteLine("Four");

        // Sleep.
        System.Threading.Thread.Sleep(10000);

One
    Two
    Three
Four

        Trace.Listeners.Add(new TextWriterTraceListener(Console.Out));
        int value = -1;
        // A.
        // If value is ever -1, then a dialog will be shown.
        Debug.Assert(value != -1, "Value must never be -1.");

        // B.
        // If you want to only write a line, use WriteLineIf.
        Debug.WriteLineIf(value == -1, "Value is -1.");

---- DEBUG ASSERTION FaiLED ----
---- Assert Short Message ----
Value must never be -1.
---- Assert Long Message ----

   at Program.Main(String[] args) in ...Program.cs:line 12

Value is -1.

        Trace.Listeners.Add(new TextWriterTraceListener(Console.Out));
        Trace.Assert(false);

Process terminated. Assertion Failed
   at Program.Main(String[] args) in C:\ConsoleApp4\Program.cs:line 44

public static void Fail(string message) {
            if (UseGlobalLock) {
                lock (critSec) {
                    foreach (TraceListener listener in Listeners) {
                        listener.Fail(message);
                        if (AutoFlush) listener.Flush();
                    }            
                }
            }
            else {
                foreach (TraceListener listener in Listeners) {
                    if (!listener.IsThreadSafe) {
                        lock (listener) {
                            listener.Fail(message);
                            if (AutoFlush) listener.Flush();
                        }
                    }
                    else {
                        listener.Fail(message);
                        if (AutoFlush) listener.Flush();
                    }
                }            
            }
        }