Comparison and logical operators

When coding, it’s often necessary to compare values or make decisions based on multiple conditions. For example, you might want to check if a number is greater than another, if two pieces of information are the same, or if multiple criteria are met simultaneously.

Python provides comparison operators for value comparison and logical operators for combining conditions to create complex logic.

Comparison operators

Comparison operators are used to compare two values and return a boolean result: True or False. These operators are the building blocks for decision-making in your code.

Equal to ==

Checks if two values are the same. For example:

print(5 == 5)  # Output: True
print(5 == 3)  # Output: False

Usage:
Use == to check if values match, such as verifying if a user’s input matches a stored password.

Not equal to !=

Checks if two values are different. For example:

print(5 != 3)  # Output: True
print(5 != 5)  # Output: False

Usage:
Use != to identify differences, like filtering out unwanted data or validating inputs.

Greater than >

Checks if one value is larger than another. For example:

print(8 > 5)  # Output: True
print(5 > 10)  # Output: False

Usage:
Useful for comparing scores, ages, or sizes.

Less than <

Checks if one value is smaller than another. For example:

print(3 < 6)  # Output: True
print(10 < 5)  # Output: False

Usage:
Use < to check conditions like whether a value is below a threshold.

Greater than or equal to >=

Checks if a value is greater than or equal to another. For example:

print(7 >= 7)  # Output: True
print(6 >= 8)  # Output: False

Usage:
Commonly used to verify minimum requirements, such as eligibility criteria.

Less than or equal to <=

Checks if a value is less than or equal to another. For example:

print(4 <= 4)  # Output: True
print(9 <= 3)  # Output: False

Usage:
Useful for scenarios like ensuring a value doesn’t exceed a maximum limit.

Logical operators

Logical operators let you combine multiple conditions into a single check. This is particularly useful when decision-making depends on more than one factor.

And and

Returns True only if both conditions are true. For example:

age = 25
is_adult = (age > 18) and (age < 65)
print(is_adult)  # Output: True

Usage:
Use and when both conditions must be true, such as checking if a number is within a specific range.

Or or

Returns True if at least one of the conditions is true. For example:

day = "Saturday"
is_weekend = (day == "Saturday") or (day == "Sunday")
print(is_weekend)  # Output: True

Usage:
Use or when any condition being true is sufficient, such as checking for multiple acceptable answers.

Not not

Reverses the result of a condition. For example:

logged_in = False
print(not logged_in)  # Output: True

Usage:
Use not to check if something is not true, such as verifying if a user isn’t logged in.

Combining comparison and logical operators

You can combine comparison and logical operators to create complex conditions. For example:

age = 20
has_ID = True

# Check if a person is allowed entry based on age and having an ID
can_enter = (age >= 18) and has_ID
print(can_enter)  # Output: True

Real-World Application:
Checking if a user meets criteria for accessing restricted content or validating multi-factor conditions.

Order of operations (Operator precedence)

Python follows a specific order when evaluating combined conditions, similar to PEMDAS in arithmetic:

1. Parentheses: ()
2. Comparison Operators: ==, !=, >, <, >=, <=
3. Logical NOT: not
4. Logical AND: and
5. Logical OR: or

Example:

x = 5
y = 10
z = 15

result = (x < y) and (y < z) or not (x == 5)
print(result)  # Output: True

Practical examples

Validating input

password = "secure123"
user_input = "secure123"

if user_input == password:
    print("Access granted.")
else:
    print("Access denied.")

Checking age for eligibility

age = 17
parental_consent = True

if (age >= 18) or (age >= 16 and parental_consent):
    print("Eligible to participate.")
else:
    print("Not eligible.")

Finding ranges

number = 25

if number > 10 and number < 50:
    print("Number is within range.")
else:
    print("Number is out of range.")

Conclusion

Comparison and logical operators are essential for making decisions in Python. They empower your code to evaluate conditions, enforce rules, and create dynamic behaviors.

By mastering these tools, you’ll unlock the ability to write programs that can respond intelligently to a wide range of scenarios.

Start practicing these operators in your projects to build stronger logic and problem-solving skills!