Pattern matching feature in CSharp 7.0

Pattern matching is a feature introduced in C# 7.0 that allows you to simplify and enhance the way you work with data and perform conditional checks in your code. It provides a more expressive and concise syntax for comparing values and extracting information from data structures. Pattern matching is a powerful addition to the language and is commonly used in scenarios like switch statements, if statements, and while loops.

Here are some key aspects of pattern matching in C# 7.0:

1. is Pattern:

   - You can use the is keyword to check if a given expression matches a certain pattern or type. This is similar to the instanceof operator in some other programming languages.

   - Example:

     if (myObject is string str)
     {
         // The myObject is a string, and you can use it as 'str' in this block.
     }
     

2. switch Statement with Patterns:

   - You can use patterns in the switch statement to match cases based on patterns rather than just constant values.

   - Example:

     switch (myObject)
     {
         case int intValue:
             Console.WriteLine($"It's an integer: {intValue}");
             break;
         case string stringValue:
             Console.WriteLine($"It's a string: {stringValue}");
             break;
         default:
             Console.WriteLine("It's something else");
             break;
     }
     

3. Pattern Variables:

   - When you use a pattern in a case statement (like int intValue in the example above), a new variable is introduced within that case block. This variable represents the matched value and can be used in that block.

4. when Clause:

   - You can further refine your pattern matching with a when clause to add additional conditions to the pattern. If the condition in the when clause is not satisfied, the pattern won't match.

   - Example:

     switch (myObject)
     {
         case int intValue when intValue > 0:
             Console.WriteLine($"Positive integer: {intValue}");
             break;
         case int intValue when intValue < 0:
             Console.WriteLine($"Negative integer: {intValue}");
             break;
         default:
             Console.WriteLine("Not an integer");
             break;
     }
     

Pattern matching in C# 7.0 simplifies code, makes it more readable, and reduces the need for explicit casting and type checking. It's particularly useful when working with complex data structures, such as parsing data from JSON or XML, and in scenarios where you need to distinguish between different types or structures of data. Later versions of C# (8.0 and beyond) have expanded on this feature, introducing additional enhancements and capabilities.