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Learn the fundamentals of C# data types, covering numeric (like int, float) and non-numeric types (such as char and bool). Understand the importance of strongly typed languages, the difference between value and reference types, and how to declare local variables and constants. Explore enumerations for organizing named constants, and practical examples demonstrating how to declare strings and read user input in C#. This guide provides essential insights for both beginners and experienced programmers.
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2. C# Language Fundamentals • Data Types • Numeric Types • Non-Numeric Types: char and bool • Variables • Definite Assignment • Constants • Strings • Statements Code Samples
Data Types • Common C# intrinsic data types
Typing in C# • C# is a strongly typed language • Types come in two flavours • Value (intrinsic) • Reference (classes …) • Each type has a name (int) and size (4b) • The .Net equivalents for int is Int32
Numeric Data Types • Unsigned (positive) • byte, ushort, uint, ulong • Signed (positive or negative) • short, int, long, float, decimal, double • Select the smallest type that will hold the required range of numbers
Non-Numeric Types: char and bool • char • Holds just a single character • Can hold: • Simple character (‘A’) • Unicode character (u\0041) • Escape character (‘\n’) • bool • Holds true or false in one byte
Declaring Local Variables int myInt; System.Console.WriteLine("Uninitialized, myInt: {0}",myInt); myInt = 5; int mySecondInt = 10; // declareand initialise int myInt4,myInt5;// declaremultiple variables What is the value on an integer before it is initialised?
Declaring Constants const int FreezingPoint = 32; // degrees Farenheit const int BoilingPoint = 212; Why would you create constants?
Declaring Enumerations An enumeration is a set of named constants // declare the enumeration enum Temperatures:int { WickedCold = 0, FreezingPoint = 32, LightJacketWeather = 60, SwimmingWeather = 72, BoilingPoint = 212, } The data type defaults to int Why would you create enumerations?
Using Enumerations System.Console.WriteLine("Freezing point of water: {0}", (int) Temperatures.FreezingPoint ); System.Console.WriteLine("Boiling point of water: {0}", (int) Temperatures.BoilingPoint );
Declaring Strings A string is an object string myString = “Hello World” ;// declareand initialise string Where would you use strings in your code?
Statements, Expressions & White Space • A statement ends in a semicolon int myInt = 23; • An expression can be part of an assignment myInt = myInt * 23; • White spaces are ignored myInt = myInt * 100;
Unit 2 Lab To write statements that prompt and greet the user 1. Open Visual Studio.Net and create a new C# Console Application project 2. In the Main method insert the following line: string myName; 3. Write a statement that prompts users for their name. 4. Write another statement that reads the user’s response from the keyboard and assigns it to the myName string. 5. Add one more statement that prints “Hello myName” to the screen (where myName is the name the user typed in). 6. Save your work.
Unit 2 Lab … When completed, the Main method should contain the following: static void Main( ) { string myName; Console.WriteLine("Please enter your name"); myName = Console.ReadLine( ); Console.WriteLine("Hello {0}", myName); }
