Python Language - Control Structures (if, elif, else, while, for)

Control Structures in Python

Control structures are fundamental elements in programming, enabling you to manage the flow of your code and make decisions based on specific conditions. In Python, you can use various control structures like if, elif, else, while, and for to control the flow of your program. In this guide, we’ll explore these control structures and their use in Python.

The if Statement

The if statement allows you to execute a block of code if a specified condition is true. Here’s an example:


x = 10
if x > 5:
    print("x is greater than 5")

If the condition in the if statement is true, the code within the block is executed. Otherwise, it is skipped.

The else Statement

The else statement works in conjunction with if. It allows you to specify a block of code to execute when the if condition is false. Here’s an example:


x = 3
if x > 5:
    print("x is greater than 5")
else:
    print("x is not greater than 5")

If the if condition is false, the code within the else block is executed.

The elif Statement

The elif statement, short for “else if,” is used when you have multiple conditions to check. It allows you to test additional conditions after an if statement. Here’s an example:


x = 5
if x > 10:
    print("x is greater than 10")
elif x > 5:
    print("x is greater than 5 but not greater than 10")
else:
    print("x is not greater than 5")

The code within the first if or elif block that evaluates to true is executed, and subsequent conditions are not checked.

The while Loop

The while loop allows you to repeatedly execute a block of code as long as a specified condition remains true. Here’s an example:


count = 0
while count < 5:
    print("Count is:", count)
    count += 1

The code within the while loop continues to execute as long as the condition (count < 5) is true. Be cautious when using while loops to avoid infinite loops.

The for Loop

The for loop is used for iterating over a sequence (such as a list, tuple, or string) or other iterable objects. It allows you to perform an action for each item in the sequence. Here’s an example:


fruits = ["apple", "banana", "cherry"]
for fruit in fruits:
    print("I like", fruit)

The for loop simplifies iterating through collections and sequences, making it a powerful tool for data processing and manipulation.

Break and Continue Statements

Within both while and for loops, you can use the break and continue statements to control the flow of the loop. break is used to exit the loop prematurely, while continue is used to skip the current iteration and move to the next. Here are examples of these statements:


# Using break
numbers = [1, 2, 3, 4, 5]
for number in numbers:
    if number == 3:
        break
    print("Number:", number)

# Using continue
numbers = [1, 2, 3, 4, 5]
for number in numbers:
    if number == 3:
        continue
    print("Number:", number)

These statements give you fine-grained control over loops, allowing you to exit early or skip specific iterations.

Conclusion

Control structures, including if, elif, else, while, and for, are essential for creating dynamic and responsive Python programs. Whether you’re making decisions, repeating actions, or iterating through data, these control structures empower you to write versatile and powerful code. Whether you’re learning Python or preparing for job interviews, mastering these fundamental control structures is crucial for becoming a proficient Python developer.

Python Language – Control Structures (if, elif, else, while, for)