String interpolation with #{} in Ruby

Introduction

String interpolation lets you put values or expressions inside a string easily.

When you want to include a variable's value inside a message.

When you want to combine text and numbers in one string.

When you want to show the result of a calculation inside a string.

When you want to build a sentence that changes based on data.

Syntax

Ruby

"Hello, #{variable_or_expression}!"

Use double quotes "" for strings with interpolation.

Inside #{}, you can put variables or any Ruby expression.

Examples

Insert the value of name inside the string.

Ruby

name = "Alice"
puts "Hello, #{name}!"

Show a number variable inside a sentence.

Ruby

age = 10
puts "You are #{age} years old."

Calculate inside the string and show the result.

Ruby

puts "5 + 3 = #{5 + 3}"

Sample Program

This program shows how to put variables inside a string using #{ }.

Ruby

name = "Bob"
age = 25
puts "My name is #{name} and I am #{age} years old."

Important Notes

Interpolation only works inside double-quoted strings, not single-quoted.

You can put any Ruby code inside #{}, like method calls or math.

Summary

Use #{ } inside double quotes to insert values or expressions into strings.

This makes building dynamic messages easy and readable.