If-Else Statement in Ruby

In this tutorial, we will learn about if-else statements in Ruby. We will cover the basics of conditional execution using if-else statements.

What is an If-Else statement

An if-else statement is a conditional statement that executes one block of code if a specified condition is true, and another block of code if the condition is false.

Syntax

The syntax for the if-else statement in Ruby is:

if condition
  # Code block to execute if condition is true
else
  # Code block to execute if condition is false
end

The if-else statement evaluates the specified condition. If the condition is true, the code block inside the if statement is executed; otherwise, the code block inside the else statement is executed.

Flowchart of If Else Statement

Example 1: Checking if a Number is Even or Odd

We can use an if-else statement to check if a given number is an even number or odd number.

For example,

  1. Declare a variable num.
  2. Assign a value to num.
  3. Use an if-else statement to check if num is even or odd.
  4. Print a message indicating whether num is even or odd.

Ruby Program

num = 10
if num % 2 == 0
  puts "#{num} is even."
else
  puts "#{num} is odd."
end

Output

10 is even.

Example 2: Checking if a String Starts with a Specific Value

We can use an if-else statement to check if a given string starts with a specific prefix.

For example,

  1. Declare a variable str.
  2. Assign a value to str.
  3. Use an if-else statement to check if str starts with a specific value.
  4. Print a message indicating the result of the check.

Ruby Program

str = 'Hello, world!'
if str.start_with?('Hello')
  puts 'String starts with 'Hello'.'
else
  puts 'String does not start with 'Hello'.'
end

Output

String starts with 'Hello'.

Example 3: Checking if a Number is Positive or Negative

We can use an if-else statement to check if a given number is a positive number or a negative number.

For example,

  1. Declare a variable num.
  2. Assign a value to num.
  3. Use an if-else statement to check if num is positive or negative.
  4. Print a message indicating whether num is positive or negative.

Ruby Program

num = -5
if num > 0
  puts "#{num} is positive."
else
  puts "#{num} is negative or zero."
end

Output

-5 is negative or zero.