What is Pattern Matching in C#?
At first pattern matching concept is introduced in C# 7.0, later versions of C# make more improvements in its functionality. Pattern Matching is a technique of comparing expressions according to the specified structures or patterns to see if there is any match or not. It provides conditional logic simpler and makes it possible to extract useful details from the structures of data(such as an expression) or an object.
Operations of Pattern Matching
Pattern matching provides us with many operations such as, “is”, and “switch” expressions, constant patterns, relational, and many more patterns. Now, we implement examples of pattern matching with C# programs.
Pattern Matching with “is” and “switch” Expression
Let’s illustrate pattern matching with “is” and “switch” expressions with the help of a below-provided example.
Example
The provided “using System” library is used at the top of the C# program to import the classes from the System namespace, such as Console, DateTime, or Math:
Now, we define a base class as “Color” and make a public function as “Show()” that simply prints a message on the screen as “Find a Color”:
{
public virtual void Show()
{
Console.WriteLine("Find a Color");
}
}
After that, we have a “Red” class which is referred to as the derived class that overrides the “Show()” method from the base class:
{
public override void Show()
{
Console.WriteLine("Find a Red Color");
}
}
Then, inside the “Program” class, the static void “Main()” function has created an array of “Color” objects, including both instances of class “Color” and “Red”.
{
static void Main()
{
Color[] colors = { new Color(), new Red() };
Moving forward, we use the “is” expression to determine the type of color whether each color is Red or not inside of the “foreach” loop. If so, it will print the “if” statement first and take particular steps. Otherwise, handle it as a regular shape.
{
if (color is Red red)
{
Console.WriteLine("It's a red color!");
red.Show();
}
else
{
Console.WriteLine("It's not a red color!");
color.Show();
}
Next, we implement the “switch” expression to match the pattern type of “Red” with the “Color” case and perform actions accordingly. In the “switch” expression, the “default” case invokes when a pattern does not match with any particular type:
switch (color)
{
case Red r:
Console.WriteLine("Switch: It's a Red Color");
r.Show();
break;
default:
Console.WriteLine("Switch: It's not a Red Color!");
color.Show();
break;
}
}
}
}
Output
You have learned pattern matching using “is” and “switch” expressions.
Conclusion
Pattern matching in C# is a versatile feature that is used to create code in more expressive ways. By leveraging pattern matching, you can make conditional logic simpler, extract data from intricate data structures, and make your code easier to read and maintain. The guide provided the usage of the “is” and “switch” expressions to check type patterns according to objects type in an effective way.
