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Conditional Statements
Switch Statements

Using multiple else if statements can get unwieldy pretty quickly. Imagine writing an else if statement for every possible number of guests. And you invited 20 people. You have to write a lot of repetitive code, which is hard to read and prone to errors.

If it’s necessary to evaluate several conditions with their own unique output, a switch statement is the way to go. Switch statements allow for compact control flow structures by evaluating a single expression and executing code blocks based on a matched case.

In C#, we write a switch statement using the following syntax:

string color; switch (color) { case "blue": // execute if the value of color is "blue" Console.WriteLine("color is blue"); break; case "red": // execute if the value of color is "red" Console.WriteLine("color is red"); break; case "green": // execute if the value of color is "green" Console.WriteLine("color is green"); break; default: // execute if none of the above conditions are met break; }

In this example, the program checks to see what the value of color equals. If it matches any of the specified cases, it will execute the code associated with that case. In C#, the break keyword allows programs to exit a block when a specific condition is met. If none of the conditions are met, the code inside the default case will run.

When using a switch statement, make sure to pay attention to:

  • Cases: rather than writing out each condition, if we’re evaluating one value we use cases to specify different potential values.
  • Braces: rather than each case having its own code block, the entire statement lives within one set of braces {}.
  • Colons: to distinguish between different cases, we state the case value, followed by a colon :. The code that should execute if that case is met follows.
  • Break: Each case code needs to end with a break keyword.
  • Default: Every switch statement needs a default case.

Instructions

1.

You want to build a simple movie recommender that gives the top movie in a particular genre.

First, create a string variable named genre and save the value "Horror" to it.

2.

Create a switch statement using genre. Don’t add any cases to the code block yet.

3.

Next, add the following movie genres as cases to the switch statement. Make sure to also add a default case. Add a break statement to each case.

Genres:

  • Drama
  • Comedy
  • Adventure
  • Horror
  • Science Fiction
4.

Next, add Console.WriteLine() statements to each case in the switch statement so that the program prints out different movie titles based on the selected genre. For the default case, print “No movie found”.

Take a look at the following table to see the top movie for five different genres:

Genre Movie
Drama Citizen Kane
Comedy Duck Soup
Adventure King Kong
Horror Psycho
Science Fiction 2001: A Space Odyssey
5.

Let’s turn this into something a user can make use of. Swap out "Horror" for Console.ReadLine() to get the user’s response and save it to genre. Before that, add a Console.WriteLine() that prompts the user to pick a genre.

Type dotnet run into the terminal to see the program in action.

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