Logical operators (&&, ||, !) in Ruby

Introduction

Logical operators help you make decisions by combining or changing true/false values.

Checking if two conditions are both true before doing something.

Doing something if at least one condition is true.

Reversing a true or false value to its opposite.

Making complex decisions by joining multiple true/false checks.

Controlling program flow based on multiple rules.

Syntax

Ruby

condition1 && condition2  # true if both are true
condition1 || condition2  # true if at least one is true
!condition               # true if condition is false

&& means AND: both sides must be true.

|| means OR: one or both sides can be true.

! means NOT: reverses true to false and false to true.

Examples

Both sides are not true, so result is false.

Ruby

true && false  # => false

At least one side is true, so result is true.

Ruby

true || false  # => true

NOT true becomes false.

Ruby

!true  # => false

Inside parentheses is true, NOT makes it false.

Ruby

!(false || true)  # => false

Sample Program

This program checks two true/false values using AND, OR, and NOT operators and prints messages based on the results.

Ruby

a = true
b = false

if a && b
  puts "Both are true"
elsif a || b
  puts "At least one is true"
else
  puts "None are true"
end

puts "Not a is #{!a}"

Important Notes

Remember, && stops checking as soon as it finds a false (short-circuit).

|| stops checking as soon as it finds a true (short-circuit).

Use parentheses to make complex conditions clear and avoid mistakes.

Summary

Logical operators combine or reverse true/false values.

&& means both must be true, || means one or both can be true, ! reverses true/false.

They help control decisions in your program.