C# Variables and Data Types

Variables and Data Types

• In C#, a variable is a name given to a storage location that holds a value.
• Data types determine the type of value a variable can hold:
  • Value types: int, float, double, bool, char, etc.
  • Reference types: string, array, class, etc.
  • Nullable types: int?, bool?, etc.

Operators

• Arithmetic operators: +, -, *, /, %, etc.
• Comparison operators: ==, !=, >, <, >=, <=
• Logical operators: &&, ||, !
• Assignment operators: =, +=, -=, *=, /=, %=, etc.

Control Structures

• Conditional statements:
  • if-else statements
  • switch statements
• Loops:
  • for loops
  • while loops
  • do-while loops
• Jump statements:
  • break
  • continue
  • return

Functions

• A function is a block of code that can be called multiple times from different parts of a program.
• Functions can take arguments and return values.
• Functions can be:
  • Instance methods
  • Static methods
  • Extension methods

Classes and Objects

• A class is a blueprint for creating objects.
• A class defines properties, methods, and events.
• Objects are instances of classes.
• Constructors are used to initialize objects.

Inheritance

• Inheritance is a mechanism that allows one class to inherit the properties and behavior of another class.
• The inherited class is called the subclass or derived class.
• The class from which the subclass inherits is called the base class or superclass.

Exception Handling

• Try-catch blocks are used to handle exceptions.
• A try block contains code that may throw an exception.
• A catch block contains code that handles the exception.
• Finally blocks are used to execute code regardless of whether an exception was thrown.

Arrays and Collections

• Arrays are fixed-size, homogeneous collections of elements.
• Collections are dynamic, heterogeneous collections of elements.
• Common collection classes:
  • List
  • ArrayList
  • Dictionary

LINQ

• LINQ (Language Integrated Query) is a set of extensions to the .NET Framework that enables querying of data.
• LINQ provides a unified way to query different data sources, such as databases, arrays, and XML files.
• Common LINQ methods:
  • Where
  • Select
  • Join
  • GroupBy
  • OrderBy

Variables and Data Types

• A variable in C# is a designated name for a storage location that holds a value.
• Data types categorize variables into specific types, defining the type of value they can hold.

Data Types

• Value types in C# include int, float, double, bool, and char, which store values directly.
• Reference types, such as string, array, and class, store memory locations of values.
• Nullable types, denoted by ?, can hold null values, e.g., int?, bool?, etc.

Operators

• Arithmetic operators in C# perform mathematical operations, including addition (+), subtraction (-), multiplication (*), division (/), modulus (%), and more.
• Comparison operators, used for conditional statements, include equals (==), not equals (!=), greater than ()), less than or equals to (=), and others.