C#

Last spring, an order import for a Texas retailer crashed because the Quantity column came back empty on a few rows. To do a C# convert null to int, keep the value in an int? and pick a fallback with ??: In this tutorial, I’ll show every C# convert null to int option I use … Read more >>

Many C# guides still teach Tuple<string, int> and a wall of Item1, Item2. It works, but it’s a heap-allocated class with names nobody can read. The modern tuple in C# is (string City, decimal Total): a light ValueTuple with real field names. In this tutorial, I’ll walk one set of store orders through every common … Read more >>

To use a Hashtable in C#, add using System.Collections;, create new Hashtable(), store pairs with Add(key, value) and cast each value back to its real type when you read it. For new code, Microsoft recommends the generic Dictionary<TKey,TValue> instead. I ran every example here on .NET 10 against one staff table, including the exceptions that … 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 >>

Status code 3 means nothing to whoever reads your code next year. Shipped means everything, and the compiler can check it for you. Quick answer: An enum in C# is a value type that gives names to a fixed set of integer constants. Declare it with enum OrderStatus { Pending, Paid, Shipped }, cast it … Read more >>

If you need to find a value by a key, like a state capital from the code “TX”, a dictionary in C# is the answer: Dictionary<TKey, TValue> maps unique keys to values and finds any key in close to constant time. In this tutorial, I’ll use one small map of US state capitals to teach … Read more >>

Last spring, a sales dashboard I was building for a US retail client crashed on one innocent line: regions[4]. The array held four regions, and index 4 simply doesn’t exist. Here’s the quick answer. A C# array is a fixed-size, zero-indexed block of values of one type, such as string[] regions = [“West”, “South”];. You … Read more >>

Dispatch software for a Texas freight client starts every morning with zero orders and ends with a few hundred. Nobody knows the final number in advance, so a fixed-size C# array is the wrong container for that list. In this tutorial, I’ll walk through List in C# the way I use it on .NET 10: … Read more >>

Leave a file handle open in a busy service and it stays open until the garbage collector notices. C# gives you two cleanup tools, Dispose and Finalize, and they behave very differently. Quick answer: In C#, Dispose() from IDisposable releases a resource the moment you call it, usually through a using statement. Finalize is the … Read more >>

Write your first interface in C#, skip one member in the class that implements it, and the build stops cold: An interface is a contract. Every class that lists it must implement every member, so adding the missing Fee method fixes CS0535. We’ll build a three-gateway checkout on .NET 10, one interface skill per step. … Read more >>