The if-else statement in Python is a control flow structure that allows you to test a condition and execute one block of code if the condition is True and another block if the condition is False.
Syntax:
if condition:
# Code block to execute if the condition is True
else:
# Code block to execute if the condition is False
The condition is an expression that evaluates to either True or False.
If the condition is True, the code inside the if block runs.
If the condition is False, the code inside the else block runs.
Example 1: Basic if-else Statement
x = 10
if x > 5:
print("x is greater than 5")
else:
print("x is not greater than 5")
Output: x is greater than 5
In this example:
The condition x > 5 is True, so the if block is executed.
Example 2: if-else with a False Condition
x = 3
if x > 5:
print("x is greater than 5")
else:
print("x is not greater than 5")
Output: x is not greater than 5
In this case:
The condition x > 5 is False, so the else block is executed.
Multiple if-else Statements (Chained if-else)
You can chain multiple if-else statements using elif (else if) to check for multiple conditions.
Syntax:
if condition1:
# Code block to execute if condition1 is True
elif condition2:
# Code block to execute if condition2 is True and condition1 is False
else:
# Code block to execute if both conditions are False
Example 3: Using if-elif-else
x = 15
if x > 20:
print("x is greater than 20")
elif x > 10:
print("x is greater than 10 but less than or equal to 20")
else:
print("x is 10 or less")
Output: x is greater than 10 but less than or equal to 20
In this case:
The first condition x > 20 is False, so it checks the next condition x > 10, which is True. Thus, the elif block is executed.
Example 4: Chained if-else for Different Ranges
age = 22
if age < 18:
print("You are a minor.")
elif age < 60:
print("You are an adult.")
else:
print("You are a senior citizen.")
Output: You are an adult.
Key Points:
if is used to check a condition, and if it’s True, the associated block of code is executed.
else provides an alternative block of code that is executed if the condition is False.
elif allows you to check multiple conditions in a sequence (useful when you have more than two options to evaluate).
if-else statements are a fundamental tool for controlling program flow based on conditions.
Let me know if you'd like more examples or a deeper explanation! 😊
0 Comments