What are the ways to use using keyword in C#?

C#'s TPL simplifies parallel task processing through the Task class. 1. Use Task.Run() or Task.Factory.StartNew() to start the task, and recommend the former; 2. Get the result through Task and wait for completion with await or .Result; 3. Use Task.WhenAll() to execute multiple tasks in parallel, pay attention to resource competition; 4. Use AggregateException to handle exceptions, and traverse specific errors after catching; 5. Use CancellationTokenSource to cancel the task, which is suitable for timeout or user cancellation scenarios; at the same time, pay attention to avoid mixing synchronous and asynchronous code to prevent deadlock problems.

There are two common ways to read text files line by line in C#: using StreamReader and File.ReadLines(). 1. The ReadLine() method of StreamReader is suitable for processing large files, read line by line through loop and is memory friendly, and uses using to ensure resource release; 2. File.ReadLines() provides concise code, suitable for scenarios that only need to be traversed once, supports lazy loading and can specify encoding. If you need to access the file content multiple times, File.ReadAllLines() is recommended. The two automatically recognize encoding by default, but to avoid garbled code, it is recommended to explicitly specify Encoding.UTF8 and Enc as needed.

C#canbeusedforscientificcomputinganddataanalysisbysettingupaproperenvironment,leveragingrelevantlibraries,andoptimizingperformance.First,installVisualStudioorVSCodewiththe.NETSDKasthefoundation.Next,useNuGetpackageslikeMath.NETNumericsforlinearalgebr

In C#, the static keyword is used to define members belonging to the type itself and can be accessed without instantiation. 1. Static variables are shared by all instances of the class and are suitable for tracking global state, such as recording the number of instantiation of the class; 2. Static methods belong to classes rather than objects, and cannot directly access non-static members, and are often used in helper functions in tool classes; 3. Static classes cannot be instantiated and only contain static members. They are suitable for organizing stateless practical methods, but cannot inherit or implement interfaces. When using it, you need to pay attention to memory management and thread safety issues.

Choosing the right collection type can significantly improve C# program performance. 1. Frequently insert or delete the LinkedList in the middle, 2. Quickly search using HashSet or Dictionary, 3. Fixed element count to use arrays first, 4. Select HashSet when unique values are required, 5. Frequently searching using Dictionary or SortedDictionary, 6. Consider ConcurrentBag or ConcurrentDictionary in multi-threaded environment.

structs are not necessarily faster, performance depends on the scenario. struct is the value type, assignment copy the entire structure, class is the reference type, assignment copy only the reference. The struct is usually allocated on the stack, and the fast but frequent passing of large structures will increase the replication overhead, and the class allocation involves GC pressure on the heap. Small structs are suitable for high-performance and cache-friendly scenarios, and large structs should be avoided or passed with ref/in. The compact memory of the struct array is conducive to caching, and the class array references are scattered to affect efficiency. Scenarios where struct are preferred: small data, short life cycle, no inheritance or virtual methods are required. Avoid using struct scenarios: large structure, complex logic, polymorphic, frequent packing, and sharing

ReadyToRun(R2R)improvesstartuptimebypre-compilingILtonativecodeduringpublish,reducingJITworkloadatruntime.2.NativeAOTcompilationeliminatestheJITentirelybycompilingtheentireapptonativecodeatbuildtime,enablingnear-instantstartup.3.UseR2Rforminimal-effo

The choice of JSON or XML depends on the application scenario: 1. The situation of using JSON includes WebAPI return data, front-end interaction, modern service communication, and lightweight configuration; 2. The situation of using XML includes legacy system compatibility, namespace support, document-based data structures, and enterprise-level application interface specifications. In C#, .NETCore uses System.Text.Json for JSON serialization by default, with better performance and supports formatted output and null value retention; XML is implemented through XmlSerializer, suitable for old projects, and can customize tag names and namespaces, but does not support circular references, and needs to be processed manually or replaced with other libraries. Rationally select and configure serialization methods to help deal with different developments