Basic Overview:

  • A nested if statement is an if statement placed inside another if, else if, or even a loop.
  • You can use nested if statements inside a for loop to perform multiple condition checks.
  • A for loop iterates through a collection (like a list) and checks various conditions using if statements in each iteration.
  • Based on the condition results, the corresponding code is executed.
numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]


for num in numbers:
    if num % 2 == 0:  # Check if the number is even
        if num > 5:  # Another condition inside the first if statement
            print(num, "is even and greater than 5")
        else:
            print(num, "is even and less than or equal to 5")
    else:  # If it's not even, it must be odd
        print(num, "is odd")


1 is odd
2 is even and less than or equal to 5
3 is odd
4 is even and less than or equal to 5
5 is odd
6 is even and greater than 5
7 is odd
8 is even and greater than 5
9 is odd
10 is even and greater than 5

Practice Problem

  • Here, there are four numbers listed. Using your knowledge of nested if statements, write code that will print the positive numbers in one group and the negative numbers as one group.
  • Helpful Hint: the command that checks if a number is negative is “if num<0”
# List of numbers
numbers = [10, -5, 7, -3]

# Your task: Write a loop with nested if statements to print whether each number is positive or negative


# <h2> Answer to the Practice Problem </h2>

numbers = [0, -3, 5, -8, 2, 0, 7, -1]
for num in numbers:
    if num == 0:  # Check if the number is zero
        print(num, "is zero")
    else:
        if num > 0:  # Check if the number is positive
            if num % 2 == 0:  # Nested if to check if it's even
                print(num, "is positive and even")
            else:  # If it's not even, it must be odd
                print(num, "is positive and odd")
        else:  # If it's not positive, it must be negative
            print(num, "is negative")

0 is zero
-3 is negative
5 is positive and odd
-8 is negative
2 is positive and even
0 is zero
7 is positive and odd
-1 is negative

What is Happening:

  • The code loops through a list of numbers.
  • For each number, it first checks if the number is even.
    • If even, it checks if the number is greater than 5.
    • If the number is not greater than 5, it prints that it is even and ≤ 5.
  • If the number is odd, it simply prints that the number is odd.

Additional Notes:

  • Multiple Conditions: Nested if statements allow you to add layers of condition checks, which is helpful when you want to ensure that several criteria are met before executing certain code.
  • Code Readability: While nested if statements provide flexibility, too many levels of nesting can make the code harder to read. Always try to keep nesting simple and clear.
  • Real-World Use: Nested if statements are commonly used in scenarios where decisions need to be made based on multiple criteria, such as filtering or categorizing data.