C#开发者必知的100个黑科技(后50)！从主构造函数到源生成器全面掌握

var sb = new StringBuilder();  
sb.Append("Hello, ");  
sb.Append("world!");  
string result = sb.ToString();  

if (int.TryParse("123", out int number))  
{  
    Console.WriteLine($"Parsed number: {number}");  
}  
else  
{  
    Console.WriteLine("Invalid input.");  
}  

enum Status { Pending, Approved, Rejected }  
Console.WriteLine(nameof(Status.Approved)); // 输出 "Approved"  

if (Enum.TryParse("Approved", out Status status))  
{  
    Console.WriteLine($"Status: {status}");  
}  

if (string.Equals("hello", "HELLO", StringComparison.OrdinalIgnoreCase))  
{  
    Console.WriteLine("Strings are equal.");  
}  

if (string.IsNullOrWhiteSpace(input))  
{  
    Console.WriteLine("Input is invalid.");  
}  

var stopwatch = Stopwatch.StartNew();  
// Your code here  
stopwatch.Stop();  
Console.WriteLine($"Elapsed time: {stopwatch.ElapsedMilliseconds} ms");  

Console.WriteLine($"Line 1{Environment.NewLine}Line 2");  

var uniqueId = Guid.NewGuid();  
Console.WriteLine($"Unique ID: {uniqueId}");  

var now = DateTimeOffset.Now;  
Console.WriteLine($"Current time: {now}");  

var duration = new TimeSpan(, , ); // 2小时30分钟  
Console.WriteLine($"Duration: {duration}");  

var uniqueNumbers = new HashSet<int> { , , ,  };  
Console.WriteLine($"Count: {uniqueNumbers.Count}"); // 输出 3  

var ages = new Dictionary<string, int>  
{  
    { "Alice",  },  
    { "Bob",  }  
};  
Console.WriteLine($"Alice's age: {ages["Alice"]"]);  

var sortedAges = new SortedDictionary<string, int>  
{  
    { "Bob",  },  
    { "Alice",  }  
};  

var concurrentAges = new ConcurrentDictionary<string, int>();  
concurrentAges.TryAdd("Alice", );  

var queue = new Queue<int>();  
queue.Enqueue();  
queue.Enqueue();  
Console.WriteLine($"Dequeued: {queue.Dequeue()}"); // 输出 1  

var stack = new Stack<int>();  
stack.Push();  
stack.Push();  
Console.WriteLine($"Popped: {stack.Pop()}"); // 输出 2  

var bits = new BitArray(new[] { true, false, true });  
Console.WriteLine($"Bit at index 0: {bits[]}"); // 输出 True  

var collection = new ObservableCollection<string>();  
collection.CollectionChanged += (sender, e) => Console.WriteLine("Collection changed!");  
collection.Add("Item 1");  

var lazyValue = new Lazy<int>(() => );  
Console.WriteLine($"Lazy value: {lazyValue.Value});  

var threadLocal = new ThreadLocal<int>(() => );  
Console.WriteLine($"Thread-local value: {threadLocal.Value});  

var semaphore = new SemaphoreSlim(); // 允许2个并发访问  
await semaphore.WaitAsync();  
// 访问资源  
semaphore.Release();  

var cts = new CancellationTokenSource();  
var task = Task.Run(() =>  
{  
    while (!cts.Token.IsCancellationRequested)  
    {  
        // Do work  
    }  
}, cts.Token);  
cts.Cancel();  

await Task.Delay(); // 模拟1秒延迟  

var task = Task.FromResult();  
Console.WriteLine($"Result: {task.Result});  

await Task.Run(() =>  
{  
    // CPU-bound work  
});  

var tasks = new[] { Task.Delay(), Task.Delay() };  
await Task.WhenAll(tasks);  

var tasks = new[] { Task.Delay(), Task.Delay() };  
var completedTask = await Task.WhenAny(tasks);  

Parallel.ForEach(Enumerable.Range(, ), i =>  
{  
    Console.WriteLine($"Processing {i}");  
});  

Parallel.Invoke(  
    () => Console.WriteLine("Action 1"),  
    () => Console.WriteLine("Action 2")  
);  

int counter = ;  
Interlocked.Increment(ref counter);  

var cache = new MemoryCache(new MemoryCacheOptions());  
cache.Set("key", "value");  
var value = cache.Get("key");  

var bag = new ConcurrentBag<int>();  
bag.Add();  
bag.TryTake(out int result);  

var collection = new BlockingCollection<int>();  
collection.Add();  
var item = collection.Take();  

var channel = Channel.CreateUnbounded<int>();  
await channel.Writer.WriteAsync();  
var item = await channel.Reader.ReadAsync();  

public class Person  
{  
    [Required]  
    public string Name { get; set; }  
}  

var regex = new Regex(@"\d+");  
var match = regex.Match("123");  
Console.WriteLine($"Match: {match.Value}");  

var person = new Person { Name = "Alice" };  
var json = JsonSerializer.Serialize(person);  
var deserialized = JsonSerializer.Deserialize<Person>(json);  

var serializer = new XmlSerializer(typeof(Person));  
using var writer = new StringWriter();  
serializer.Serialize(writer, person);  

using var stream = new FileStream("file.txt", FileMode.Open);  
// Read or write to the file  

using var reader = new StreamReader("file.txt");  
var content = reader.ReadToEnd();  

var fullPath = Path.Combine("folder", "file.txt");  
Console.WriteLine($"Full path: {fullPath}");  

var files = Directory.GetFiles("folder");  

var watcher = new FileSystemWatcher("folder");  
watcher.Created += (sender, e) => Console.WriteLine($"File created: {e.Name}");  
watcher.EnableRaisingEvents = true;  

var client = new HttpClient();  
var response = await client.GetAsync("https://example.com");  

var websocket = new ClientWebSocket();  
await websocket.ConnectAsync(new Uri("wss://example.com"), CancellationToken.None);  

var socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);  
socket.Connect("example.com", );  

var process = new Process  
{  
    StartInfo = new ProcessStartInfo("notepad.exe")  
};  
process.Start();  

Console.WriteLine($"OS Version: {Environment.OSVersion});  

var domain = AppDomain.CreateDomain("NewDomain");  
domain.ExecuteAssembly("app.exe");