The last activity introduced the concept of controlling an application’s flow using if statements. We used an age validator app that executed code only when an if statement’s condition evaluated to true. However, there are many cases where only one of several options should run—for instance, one outcome or the other.
We can extend an if statement to include other types of statements: else if and else.
else if follows an if statement and only checks its condition if the preceding if condition is false. You can chain multiple else if statements, but each must come after the initial if.else comes at the end of an if or else if chain. It has no condition of its own and executes only if all preceding conditions are false. In other words, you can think of else as a fallback or safety.Example
Console.Write("Enter your age: ");
string input = Console.ReadLine();
int age = Convert.ToInt32(input);
if (age >= 16)
{
Console.WriteLine("You are old enough to drive!");
}
else if (age == 15)
{
Console.WriteLine("You can't drive on your own yet, but you are eligible for a learner’s permit.");
}
else
{
Console.WriteLine("I'm sorry, but you are not old enough to drive.");
}
else if and elseConsole.WriteLine("--- Demo 1 - Zodiac Calendar ---\n");
Console.Write("Enter your birth year: ");
string input = Console.ReadLine();
int year = Convert.ToInt32(input);
int zodiacNumber = year % 12;
Console.Write($"\nYour birth year was {year}, so you were born the year of the ");
if (zodiacNumber == 0)
{
Console.WriteLine("monkey");
}
else if (zodiacNumber == 1)
{
Console.WriteLine("rooster");
}
else if (zodiacNumber == 2)
{
Console.WriteLine("dog");
}
else if (zodiacNumber == 3)
{
Console.WriteLine("pig");
}
else if (zodiacNumber == 4)
{
Console.WriteLine("rat");
}
else if (zodiacNumber == 5)
{
Console.WriteLine("ox");
}
else if (zodiacNumber == 6)
{
Console.WriteLine("tiger");
}
else if (zodiacNumber == 7)
{
Console.WriteLine("rabbit");
}
else if (zodiacNumber == 8)
{
Console.WriteLine("dragon");
}
else if (zodiacNumber == 9)
{
Console.WriteLine("snake");
}
else if (zodiacNumber == 10)
{
Console.WriteLine("horse");
}
else
{
Console.WriteLine("sheep");
}
Console.WriteLine("\nPress enter to continue...");
Console.ReadLine();
Console.WriteLine("\n--- Demo 2 - ATM Demo ---\n");
Console.Write("Set your initial balance: $");
input = Console.ReadLine();
double balance = Convert.ToDouble(input);
Console.WriteLine("------------------------");
Console.WriteLine("Select an option: ");
Console.WriteLine("1) View Balance");
Console.WriteLine("2) Deposit");
Console.WriteLine("3) Withdraw");
// We're not doing arithmetic with the input, so it's okay to leave it as a string.
Console.Write("Enter your option (1,2,3): ");
string option = Console.ReadLine();
if (option == "1")
{
Console.WriteLine($"Your balance is ${balance}.");
}
else if (option == "2")
{
Console.Write("How much would you like to deposit? $");
input = Console.ReadLine();
double deposit = Convert.ToDouble(input);
balance = balance + deposit;
Console.WriteLine($"Thank you for your deposit of ${deposit}.");
Console.WriteLine($"Your balance is now ${balance}.");
}
else if (option == "3")
{
Console.Write("How much would you like to withdraw? $");
input = Console.ReadLine();
double withdraw = Convert.ToDouble(input);
balance = balance - withdraw;
Console.WriteLine($"Thank you for your withdraw of ${withdraw}.");
Console.WriteLine($"Your balance is now ${balance}.");
}
else
{
Console.WriteLine("Invalid option. Exiting...");
}
--- Zodiac Calendar ---
Enter your birth year: 1990
Your birth year was 1990, so you were born the year of the horse
--- ATM Demo ---
Set your initial balance: $1200
Simple ATM
------------------------
Select an option:
1) View Balance
2) Deposit
3) Withdraw
Enter your option (1,2,3): 2
How much would you like to deposit? $75.95
Thank you for your deposit of $75.95.
Your balance is now $1275.95.