Python If ... Else

Here are some examples of Python code using the if...else construct, along with step-by-step explanations for each:

Example 1: Basic If...Else

x = 10

if x > 5:
    print("x is greater than 5")
else:
    print("x is not greater than 5")

Explanation:

• x is assigned the value of 10.
• The if statement checks whether x is greater than 5.
• If the condition is true, it executes the indented block under if.
• If the condition is false, it executes the indented block under else.

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Example 2: Checking Odd or Even

num = 7

if num % 2 == 0:
    print("Number is even")
else:
    print("Number is odd")

Explanation:

• num is assigned the value of 7.
• The if statement checks if num modulo 2 is equal to 0 (i.e., if it's an even number).
• If the condition is true, it prints "Number is even"; otherwise, it prints "Number is odd".

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Example 3: Nested If...Else

age = 18

if age >= 18:
    print("You are an adult")
    if age >= 21:
        print("You can also drink alcohol")
else:
    print("You are a minor")

Explanation:

• The outer if checks if age is greater than or equal to 18.
• If true, it prints "You are an adult" and checks if age is also greater than or equal to 21.
• If the inner condition is true, it prints "You can also drink alcohol".
• If the outer condition is false, it prints "You are a minor".

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Example 4: Multiple Conditions

score = 75

if score >= 90:
    print("Grade: A")
elif score >= 80:
    print("Grade: B")
elif score >= 70:
    print("Grade: C")
else:
    print("Grade: F")

Explanation:

• The if checks if score is greater than or equal to 90.
• If true, it prints "Grade: A".
• If false, it checks the next condition (elif) for 80, and so on.
• If no conditions are true, it prints "Grade: F".

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Example 5: Ternary Operator

num = 8
result = "Even" if num % 2 == 0 else "Odd"
print(result)

Explanation:

• This uses the ternary operator (if...else in a single line) to assign a value to the result variable based on whether num is even or odd.

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Example 6: String Comparison

word = "hello"

if word == "hello":
    print("The word is hello")
else:
    print("The word is not hello")

Explanation:

• The if checks if the value of word is equal to the string "hello".
• If true, it prints "The word is hello"; otherwise, it prints "The word is not hello".

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Example 7: Checking for Empty List

my_list = []

if my_list:
    print("The list is not empty")
else:
    print("The list is empty")

Explanation:

• The if checks if the list my_list is not empty (evaluates to True).
• If true, it prints "The list is not empty"; otherwise, it prints "The list is empty".

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Example 8: Checking for None

value = None

if value is not None:
    print("The value is not None")
else:
    print("The value is None")

Explanation:

• The if checks if the variable value is not None.
• If true, it prints "The value is not None"; otherwise, it prints "The value is None".