- 01Getting Started
- 02Your First Output (Console.WriteLine)
- 03Working with Variables
- 04Conditionals (if statements)
- 05Loops (for statements)
- 06Writing a Method (Function)
- 07Working with Arrays
- 08Loops (while statements)
- 09Classes (Object-Oriented Programming)
- 10Error Handling (try-catch)
- 11Sorting an Array
- 12Recursive Functions
- 13Using the Standard Library
- 14The switch Statement
- 15The Ternary Operator
- 16Inheritance (Extending a Class)
- 17Writing Comments
- 18Logical Operators (&&, ||, !)
- 19Constants (const)
- 20Splitting and Joining Strings (Split, Join)
- 21Writing Null-Safe Code (the ?? operator)
- 22Searching an Array (Looking Through It in a Loop)
- 23Transforming an Array (LINQ Select)
- 24Two-Dimensional Arrays (Tabular Data)
- 25Writing a Custom Exception Class
- 26Default Parameter Values
- 27Working with HashSet (Sets)
- 28Checking Correctness (Your First Step into Testing)
- 29Higher-Order Functions (Passing a Function as an Argument)
- 30Stacks and Queues (Basic Data Structures)
- 31Type Conversion (Casting) Basics
- 32Intro to Regular Expressions (Pattern Matching)
- 33The Binary Search Algorithm
- 34Building a Caesar Cipher (a Character-Shifting Cipher)
- 35Understanding How Bubble Sort Works
- 36Building and Displaying Dates (Basic Year/Month/Day Operations)
- 37Writing Multiple Test Cases Together
- 38Speeding Up Calculations with Memoization (Caching)
- 39Normalizing Strings (Trim, Unifying Case)
- 40Shallow Copy vs. Deep Copy
- 41Enum (Enumerated Types) Basics
- 42Flattening an Array
- 43Reversing a String and Checking for Palindromes
- 44Pairing Up Two Arrays (the zip operation)
- 45Rounding Numbers (Floor, Ceiling, Round)
- 46Multi-Line Strings (Verbatim Strings)
- 47Functions That Return Multiple Values (Tuples)
- 48Finding the GCD and LCM (the Euclidean Algorithm)
- 49Formatting Numbers (Padding Digits, Decimal Places)
- 50Cleanup Logic with try/catch/finally
- 51Writing Generic Functions
- 52File Reading and Writing Basics
- 53Generating Random Numbers
- 54Bitwise Operators (AND, OR, XOR, shifts)
- 55Reading Command-Line Arguments
- 56Waiting for a Fixed Amount of Time (Thread.Sleep)
- 57Watch Out for Floating-Point Rounding Errors
- 58Reading from Standard Input
- 59FizzBuzz (the Classic Practice Problem)
- 60Checking Whether a Number Is Prime
- 61Set Operations with HashSet (Union, Intersection, Difference)
- 62Converting Number Bases (Binary, Hex)
- 63Checking Balanced Parentheses (an Application of Stacks)
- 64Checking Whether Two Words Are Anagrams
- 65Checking Whether a Year Is a Leap Year
- 66Converting Temperature (Celsius to Fahrenheit)
- 67Prime Factorization
- 68[Applied] Build a Simple Inventory Management Tool
Using the Standard Library
In this lesson you will learn about handy features that ship with the C# standard library, so you know what you do not have to build yourself. This is for anyone searching for "C# standard library how to use".
Methods such as .ToUpper() and .PadLeft(), and collections such as List<T>, are used constantly in practice. .NET comes with a rich standard library.
The sample code shows "hello".ToUpper() converting to upper case, "7".PadLeft(3, '0') padding with zeros, and List<int> holding a variable-length list. Notice how .Count reads the number of elements.
A common stumbling block for beginners is not knowing what the standard library already provides, and writing the same logic out at length by hand. Knowing what exists dramatically changes how much you have to implement yourself.
In real-world development, having a working knowledge of the string and collection methods makes you noticeably faster at writing code.
๐งช This site can't compile or run C# directly, so it checks on the spot whether what you typed matches the reference code (scoring happens entirely in your browser โ nothing is sent anywhere).