Ruby Comparison And Logical Operators

Ruby Comparison Operators

Comparison operators compare two values and return a boolean result (true or false). For example,

a = 3
b = 2

puts a > b

# Output: true

Here, we used the > comparison operator to check whether a (which is 3) is greater than b (which is 2).

Since 3 is greater than 2, the output is true.

Note: In the above example, a > b is called a boolean expression because it evaluates to a boolean value (true or false).

Commonly Used Comparison Operators

1. Ruby Equal To Operator

The equal to operator == evaluates to

• true - If the values of the operands are equal.
• false - If the values of the operands are not equal.

Note: In Ruby, == is a comparison operator, whereas = is an assignment operator. If you mistakenly use = instead of ==, you might get unexpected results.

Example

num1 = 10
num2 = 15
num3 = 10
string_num = "10"

# Compare numbers with numbers
puts num1 == num2   # false
puts num1 == num3   # true

# Compare number with string
puts num1 == string_num   # false

Here's how this program works:

# Comparing identical integer and float values
puts 4 == 4.0

# Output: true

2. Not Equal To Operator

The not equal to operator != evaluates to

• true - If the values of the operands aren't equal.
• false - If the values of the operands are equal.

Example

num1 = 10
num2 = 15
num3 = 10
string_num = "10"

# Compare numbers with numbers
puts num1 != num2   # true
puts num1 != num3   # false

# Compare number with string
puts num1 != string_num  # true

Note: The != operator returns the opposite result of the == operator.

3. Greater Than Operator

The greater than operator > returns

• true - If the left operand is greater than the right operand.
• false - If the left operand is not greater than the right operand.

Example

num1 = 10
num2 = 15

# Left operand is smaller
puts num1 > num2   # false

# Left operand is greater
puts num2 > num1   # true

# Both operands are equal
puts num1 > 10   # false

4. Greater Than Or Equal To Operator

The greater than or equal to operator >= returns

• true - If the left operand is greater than or equal to the right operand.
• false - If the left operand is less than the right operand.

Example

num1 = 10
num2 = 15

# Left operand is smaller
puts num1 >= num2   # false

# Left operand is greater
puts num2 >= num1   # true

# Both operands are equal
puts num1 >= 10   # true

5. Less Than Operator

The less than operator < returns

• true - If the left operand is less than the right operand.
• false - If the left operand is not less than the right operand.

Example

num1 = 10
num2 = 15

# Left operand is smaller
puts num1 < num2   # true

# Left operand is greater
puts num2 < num1   # false

# Both operands are equal
puts num1 < 10   # false

6. Less Than Or Equal To Operator

The less than or equal to operator <= returns

• true - If the left operand is less than or equal to the right operand.
• false - If the left operand is greater than the right operand.

Example

num1 = 10
num2 = 15

# Left operand is smaller
puts num1 <= num2   # true

# Left operand is greater
puts num2 <= num1   # false

# Both operands are equal
puts num1 <= 10   # true

7. Combined Comparison Operator

The combined comparison operator <=> returns

• -1 if the left operand is less than the right operand.
• 1 if the left operand is greater than the right operand.
• 0 if both operands are equal.

Note: The <=> operator is also known as the spaceship operator.

Example

num1 = 10
num2 = 15

# Left operand is smaller
puts num1 <=> num2   # -1

# Left operand is greater
puts num2 <=> num1   # 1

# Both operands are equal
puts num1 <=> 10   # 0

Ruby Logical Operators

Logical operators return a boolean value by evaluating boolean expressions. For example,

x = 5
y = 3

puts (x < 6) && (y < 5)

# Output: true

Here, && is the logical operator AND.

Since both the boolean expressions x < 6 and y < 5 are true, evaluating them with the && operator also results in true.

Commonly Used Logical Operators

1. Logical AND Operator (&&)

The logical AND operator && returns true if both the expressions are true. For example,

x = 2

# Both expressions are true
puts (x < 4) && (3 >= x)    # true

# Only one expression is true
puts (x <= 4) && (x == 3)   # false

# Both expressions are false
puts (x > 4) && (x == 3)   # false

Here's how the program works:

2. Logical OR Operator ( || )

The logical OR operator || returns true if at least one expression is true. For example,

x = 2

# Both expressions are true
puts (x < 4) || (3 >= x)    # true

# Only one expression is true
puts (x <= 4) || (x == 3)   # true

# Both expressions are false
puts (x > 4) || (x == 3)   # false

Here's how the program works:

3. Logical NOT Operator ( ! )

The logical NOT operator ! returns true if the specified expression is false and vice versa. For example,

x = 2

# NOT on true
puts !true   # false

# NOT on false
puts !false   # true

# Comparison examples
puts !(x > 3)   # true
puts !(x == 2)  # false

Here's how the program works:

# Less than operator
puts 4 < 5

# Output: true

# Logical NOT
puts !(4 < 5)

# Output: false