Summary - Conditionals

C# course · Beginner · Lesson 41/116

Combine if, switch and pattern matching to write a day-of-week app.

Summary - Conditionals

In this group you learned if, else if, switch, switch expressions and the ternary operator. Now you will combine them to write a day-of-week app.

Across two exercises you will first produce the day name with a switch expression, then decide weekday or weekend with if/else. Each tool reads best in its own spot.

Exercise Produce the day name with a switch expression

Declare a day variable with the value 4. Use a switch expression to produce name: 1 => "monday", 2 => "tuesday", 3 => "wednesday", 4 => "thursday", _ => "?". Print name with Console.WriteLine.

Show example solution

Write string name = day switch { 1 => "monday", 2 => "tuesday", 3 => "wednesday", 4 => "thursday", _ => "?" };
Example solution:
using System;

class Program
{
    static void Main()
    {
        int day = 4;
        string name = day switch { 1 => "monday", 2 => "tuesday", 3 => "wednesday", 4 => "thursday", _ => "?" };
        Console.WriteLine(name);
    }
}

Exercise Weekday or weekend with if/else

Declare a day variable with the value 6. Use if to check day == 6 || day == 7; when it holds print "weekend" with Console.WriteLine, otherwise print "weekday" in the else branch.

Show example solution

Write if (day == 6 || day == 7) { Console.WriteLine("weekend"); } else { Console.WriteLine("weekday"); }
Example solution:
using System;

class Program
{
    static void Main()
    {
        int day = 6;
        if (day == 6 || day == 7)
        {
            Console.WriteLine("weekend");
        }
        else
        {
            Console.WriteLine("weekday");
        }
    }
}

The conditionals side by side

You now know five conditional tools: if, else if, switch, switch expressions and the ternary. Which one to pick depends on the context.

For a simple two-way pick the ternary is shortest; for two or three branches an if/else if chain; for many equality checks a switch or switch expression reads best. Prefer explicit branches over nested ternaries.

Test yourself

In a switch expression, which one means 'all other cases'?
```
var label = day switch { 1 => "one", _ => "?" };
```
- _
- default
- *
- else
Show answer

_ — Correct. _ (discard) catches all other cases.

Weekend with if/else

int day = 6;
if (day == 6 || day == 7)
{
    Console.WriteLine("____");
}
else
{
    Console.WriteLine("weekday");
}

Show answer

int day = 6;
if (day == 6 || day == 7)
{
    Console.WriteLine("weekend");
}
else
{
    Console.WriteLine("weekday");
}

Summary - Conditionals