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Cheat sheets
122 cheat sheets and notes
All cheat sheets
122 results
- PDFFree
C# First Program, Build and Run Companion
Build and run a complete C# invoice calculator with exact project files, culture-safe input and output, error handling, and eight executable checks. Includes worked transcripts and reproducible .NET 10 exercises.
18 pages · 95 KB · C# Language
- PDFFree
C# Console Design and Testing Companion
Build a three-project C# invoice application with a thin console boundary, reusable calculation library, and a standalone test harness. Work through parsing, rounding, validation, overflow, and a deliberate test failure with exact .NET 10 examples.
15 pages · 76 KB · C# Language
- PDFFree
C# Compiler Diagnostics and Build Confidence Companion
Diagnose and repair syntax, type, and nullable-reference problems with complete .NET 10 projects. Compare warning policies, inspect runtime validation, and check exact output streams and exit codes using worked compiler and port-validation examples.
16 pages · 92 KB · C# Language
- PDFFull Access
ASP.NET Core Cache Correctness Lab Companion
A worked .NET 10 lab on tenant-safe keys, expiration and stale fills, and bounded concurrent cache misses. Includes complete projects, deterministic checks, expected outputs, and applied explanations for the Cache Correctness course.
40 pages · 147 KB · Data Access in .NET
- ArticleFree
Deferred Execution and Repeated Enumeration in LINQ to Objects
Learn when a LINQ to Objects query actually runs, why enumerating the same query twice repeats work, and how that differs from database query translation and execution.
C# Language
- NoteFree
Cache Keys, Tenant Boundaries, and Cache-Aside Reads
Learn how to design cache keys that isolate tenants and users, and how cache-aside reads improve performance without ever replacing authorization checks.
Data Access in .NET
- ArticleFree
Allocation-Aware Parsing with ReadOnlySpan<char> in C#
Learn how ReadOnlySpan<char> lets you parse text without copying substrings, how slicing preserves views into the same input, and why ref-struct lifetime rules prevent spans from escaping safe scope boundaries.
.NET Runtime and Concurrency
- ArticleFull Access
Safe ArrayPool<byte> Ownership and Finally-Based Returns
Learn how to rent byte buffers from ArrayPool<byte> safely: track the valid slice length, treat the rent as borrowed ownership, and always return it in finally even when exceptions happen.
.NET Runtime and Concurrency
- NoteFull Access
Absolute and Sliding Expiration with Invalidation Races
Learn how absolute and sliding expiration control cache-entry lifetime, why each one can go wrong under real traffic, and how invalidation races create stale-data windows during concurrent reads and writes.
Data Access in .NET
- NoteFull Access
Concurrent Cache Misses and Bounded Stampede Protection
When many requests miss the same cache key at once, they can all fall through to the database and amplify load. This lesson shows how to cap the rebuild work without assuming distributed locking.
Data Access in .NET
- NoteFree
ReadOnlyMemory and ReadOnlySpan Across Async Boundaries
Learn how ReadOnlySpan and ReadOnlyMemory differ at async boundaries, why spans are stack-only views, and how ownership of rented buffers stays with the owner until consumers finish.
.NET Runtime and Concurrency
- NoteFree
IDisposable vs GC: Two Resource Lifetimes
Learn why IDisposable is about deterministic ownership cleanup, while garbage collection is about reclaiming unreachable managed memory. This lesson shows how using, try/finally, and ownership boundaries fit together in interviews.
.NET Runtime and Concurrency
- NoteFree
C# Copies Values and References Differently
Learn how C# assignment behaves for value types and reference types, why copies can be independent or shared, and why memory location is a separate question.
C# Language
- ArticleFree
Working with bool, char, and string in Everyday C#
Learn how C# boolean, character, and string types behave in real code, including comparisons, text handling, and common pitfalls that matter in production.
C# Language
- ArticleFree
Generic Types and Generic Methods in C#
Learn how C# generics let you reuse algorithms and data structures without giving up compile-time type safety or resorting to casts.
C# Language
- ArticleFree
Cancellation Tokens in Async C# APIs: Cooperative Shutdown
Learn how to design, pass, and honor CancellationToken in async C# APIs so callers can stop work cooperatively without leaking tasks or hiding late failures.
.NET Runtime and Concurrency
- ArticleFree
Choosing Between StringBuilder and String Concatenation in C#
Learn when plain concatenation, interpolation, or StringBuilder is the right tool for building text in C# based on workload, readability, and allocation behavior.
C# Language
- NoteFree
Allocation Rate vs Retained Heap in .NET Memory Tuning
Understand why allocation rate and retained managed heap measure different performance problems, how to read them together, and why a high allocation rate can still be compatible with a small live heap.
.NET Runtime and Concurrency
- ArticleFree
Loop-Variable Capture Pitfalls in C# Lambdas and Callbacks
Learn why callbacks inside loops can all observe the same changing variable, how C# fixed foreach capture semantics, and how to write safe per-iteration closures in modern code.
C# Language
- ArticleFree
String Immutability in C#: Allocations, Sharing and Surprises
Learn why C# strings never change in place, how assignment shares references, and when string operations allocate a new result or reuse an existing instance.
C# Language