If Statement in Ruby

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

What is an If statement

An if statement is a conditional statement that executes a block of code if a specified condition is true.

Syntax

The syntax for the if statement in Ruby is:

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

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

The following is the flowchart of how execution flows from start to the end of an if statement.

Flowchart of If Statement

Example 1: Checking if a Number is Even

We can use an if statement to check if a given number is an even number.

For example,

  1. Declare a variable num.
  2. Assign a value to num.
  3. Use an if statement to check if num is even.
  4. Print a message indicating whether num is even or not.

Ruby Program

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

Output

String starts with "Hello".

Example 3: Checking if a Number is Positive

We can use an if statement to check if a given number is a positive number.

For example,

  1. Declare a variable num.
  2. Assign a value to num.
  3. Use an if statement to check if num is positive.
  4. Print a message indicating whether num is positive or not.

Ruby Program

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

Output