Control Structures and Flow Control in Elixir

What You’ll Learn 📚

• Understanding control structures in Elixir
• Using if, unless, and case statements
• Working with loops using for and Enum.each
• Common pitfalls and how to avoid them

Introduction to Control Structures

Control structures are the backbone of programming logic. They help us decide the flow of our code based on certain conditions. In Elixir, we have several control structures that allow us to make decisions and repeat actions. Let’s start with some key terminology:

• Conditionals: These are statements that execute code based on whether a condition is true or false.
• Loops: These allow us to repeat a block of code multiple times.

The Simplest Example: Using if

# A simple if statement in Elixir
age = 18

if age >= 18 do
  IO.puts("You are an adult.")
else
  IO.puts("You are a minor.")
end

Progressively Complex Examples

Example 1: Using unless

# Using unless to check a condition
is_raining = false

unless is_raining do
  IO.puts("Let's go for a walk!")
else
  IO.puts("Better stay inside.")
end

Example 2: Using case

# Using case to match patterns
weather = :sunny

case weather do
  :sunny -> IO.puts("It's a bright day!")
  :rainy -> IO.puts("Don't forget your umbrella.")
  _ -> IO.puts("Weather unknown.")
end

Example 3: Looping with for

# Using for to loop through a list
numbers = [1, 2, 3, 4, 5]

for n <- numbers do
  IO.puts(n)
end

Common Questions and Answers

1. What is the difference between if and unless?

   If executes the block when the condition is true, while unless executes when the condition is false.

2. How does case work in Elixir?

   Case is used for pattern matching. It checks the value against different patterns and executes the matching block.

3. Can I use loops like while in Elixir?

   Elixir doesn't have a while loop, but you can use recursion or Enum.each for iteration.

4. Why doesn't my if statement work?

   Ensure your condition is correct and that you're using the right syntax. Remember, Elixir is case-sensitive!

5. What are some common mistakes with case?

   Forgetting the _ wildcard for unmatched cases can lead to errors.

Troubleshooting Common Issues

Always ensure your conditions and patterns are correctly defined. Syntax errors are common when starting out, so double-check your code for typos!

Practice Exercises

• Write a program that uses if to check if a number is positive, negative, or zero.
• Create a case statement that matches different types of fruits and prints a message for each.
• Use a for loop to iterate over a list of names and print a greeting for each.

Remember, practice makes perfect! The more you experiment with these concepts, the more comfortable you'll become. Keep coding! 💪

For more information, check out the Elixir documentation.