Questions
C# questions
Choose a question page, learn the concept, then test your understanding with a quiz.
Debug EntityValidationErrors in Entity Framework 6 C#
Learn how to inspect DbEntityValidationException errors in Entity Framework 6, fix invalid seed data, and configure multiple foreign keys in C#.
Declarative vs Imperative Programming in C#: A Practical Guide
Learn the difference between imperative and declarative programming in C# with clear examples, LINQ, comparisons, and practical exercises.
Deep Copy and Object Cloning in C#
Learn how deep copying and object cloning work in C#, with practical examples, pitfalls, and safe ways to duplicate objects.
Delete Directory Contents While Keeping the Root Folder in C#
Learn how to delete all files and subdirectories from a C# directory while preserving the root folder, with safe examples and common pitfalls.
Deserialize JSON into a C# dynamic Object
Learn how to deserialize JSON into a C# dynamic object, when to use it, its trade-offs, and practical examples with JSON libraries.
Does C# Have Extension Properties? Understanding Extension Methods and Alternatives
Learn whether C# supports extension properties, why it does not, and how to use extension methods or wrappers instead.
Does try-catch Make C# Code Faster? Understanding Benchmarking, JIT Optimization, and Microbenchmarks
Learn why try-catch can appear faster in C#, and how JIT behavior, CPU timing, and poor microbenchmarks can mislead results.
Dynamic OrderBy Strings for IEnumerable and IQueryable in C#
Learn how Dynamic LINQ string-based OrderBy works with IQueryable and IEnumerable, including AsQueryable, safe alternatives, and sorting examples.
Encrypt and Decrypt Strings in C# with AES-GCM
Learn how to encrypt and decrypt strings securely in C# using AES-GCM, nonces, authentication tags, UTF-8, and safe key handling.
Expression<Func<T>> vs Func<T> in C#: What’s the Difference and When to Use Each?
Learn when to use Expression<Func<T>> instead of Func<T> in C#, with clear examples, execution differences, and real-world LINQ usage.
Fast Entity Framework Bulk Inserts: Batching, AddRange, and Transactions
Learn faster Entity Framework inserts with batching, AddRange, change tracking, bulk-copy options, and safe transaction timeout strategies.
Field vs Property in C#: What’s the Difference and When to Use Each
Learn the difference between fields and properties in C#, when to use each one, and how encapsulation affects real-world class design.
File Uploads in ASP.NET MVC 3 with HttpPostedFileBase
Learn to upload files in legacy ASP.NET MVC 3 using a multipart form, HttpPostedFileBase, validation, and safe server-side storage.
First vs FirstOrDefault vs Take(1) in LINQ with C#
Learn when to use First, FirstOrDefault, and Take(1) in LINQ with C#. Understand exceptions, defaults, and practical usage patterns.
Fix IIS Metabase Access Errors in Visual Studio 2012
Learn why Visual Studio 2012 cannot access the IIS metabase and how IIS features, permissions, and project settings resolve the error.
Fix Open DataReader Errors in Entity Framework LINQ (C#)
Learn why Entity Framework throws an open DataReader error during nested LINQ queries and fix it with materialization or a single query.
Fixing "Could Not Find ... bin\roslyn\csc.exe" in ASP.NET MVC
Learn why ASP.NET MVC looks for bin\roslyn\csc.exe, what Roslyn packages do, and how to fix this missing compiler error safely.
Fixing Assembly Manifest Mismatch in C# (.NET): The Located Assembly's Manifest Definition Does Not Match the Assembly Reference
Learn why C# assembly manifest mismatch errors happen, how to find old DLL references, and how to fix version conflicts in .NET projects.
Format Decimal Values to 2 Decimal Places in C#
Learn how to display C# decimal values with exactly two decimal places using ToString format specifiers, rounding rules, and culture-aware currency formats.
Format a C# DateTime as yyyyMMddHHmmss
Learn how to format C# DateTime values as yyyyMMddHHmmss using custom format strings, correct date tokens, UTC, and culture-safe output.