The first bug most beginners hit with variables in C# isn’t a crash. It’s a build that refuses to start, because a local variable might be read before it has a value: Quick answer: give it a value on every path, like decimal discount = 0m;. Below, I run that fix and the rest of … Read more >>

Every variable you declare picks one of the data types in C#, and they come in two families. Value types like int, double, decimal, bool and char hold the data itself; reference types like string, object and arrays hold a reference to it: It prints: Below, the sizes and ranges come straight from sizeof and … Read more >>

Say you’re building order intake for a Seattle coffee roaster. Every order needs a customer, a five-digit ZIP code and at least one pound of beans, and a half-built order should never exist. Quick answer: a constructor in C# is the method named after the class, with no return type, that runs on new. That’s … Read more >>

An ArrayList in C# is a resizable list from System.Collections that stores everything as object. Create it with new ArrayList(), call Add, and cast each item back when you read it: Output: I ran every example below on .NET 10, including the casting errors, and finished by converting the list to the List<T> Microsoft recommends … Read more >>

The first do while loop in C# that most people write fails before it ever runs. Look at the end of the loop: What dotnet run prints: The compiler wants a semicolon after while (tries < 3); add it and it prints 3. It’s the only C# loop that ends in ;, and it always … Read more >>

Say you’re coding accounts for a small Columbus, Ohio credit union. Checking pays a $5 fee under $1,500, savings earns 3% a year, and nobody may type a balance in directly. Those rules map straight onto the OOPs concepts in C#: a class for the account, encapsulation to guard the balance, inheritance and polymorphism for … Read more >>

To write functions in C#, you declare a method: a return type, a name, parameters in parentheses and a body. C# calls every function a method, and in a .NET 10 file-based app you can write one right next to your top-level code: Quick answer: use a static method when it only needs its parameters, … Read more >>

To convert a char array to string in C#, pass the array to the string constructor: new string(chars). It copies every character into a new string in one call. If you’ve tried chars.ToString() first, you’ve probably seen System.Char[] instead of your text. Arrays don’t override ToString(), so you get the type name. I ran every … Read more >>

Say you’re cleaning up an old order tracker for a Columbus coffee roaster, and it keeps daily order counts in an ArrayList. Every int that goes in gets copied into a new object on the heap, and every read needs a cast back. That’s boxing and unboxing in C#, and the tracker pays for it … Read more >>