Conditionals

Conditionals execute a block of code based on a condition.

General structure#

if condition
  instructions
elif condition
  instructions
else
  instructions

Indentation

Instructions must have more left margin than the if, elif or else line.

Basic condition#

age = 23
if age >= 18
  print "You are of legal age"

How does it work?

A condition is any value or expression that can be represented as true or false. If it’s true, the corresponding code block is executed.

age = 23
condition = age >= 18  # true

if condition  # it's met
  print "The condition is " condition

If we use another type of value, its boolean representation will be attempted. You can review this representation in Truthy values.

text = "Hello"
if text
  print "The text is not empty"

Condition with `elif`#

The elif is executed only if the previous condition failed.

age <- "Enter your age: "
if age >= 18
  print "You are of legal age"
elif age >= 13
  print "You are a teenager"
elif age >= 6
  print "You are a child"

Multiple elif

You can add as many elif branches as you need after an if.
Only one of the conditional blocks is executed, the first one to be true.

Condition with `else`#

The else is executed if none of the previous conditions are met.

age <- "Enter your age: "
if age >= 18
  print "You are of legal age"
elif age >= 13
  print "You are a teenager"
else
  print "You are a minor"

Single else

There can only be one else block at the end of a conditional structure.

Combine conditions#

Use and or or:

age = 16
if age >= 13 and age < 18
  print "You are a teenager"
else
  print "You are not a teenager"

Logical operators

To review more about logical operators (and, or, not), consult the Operators section.