Understanding Control Structures in Python

Control structures are the building blocks of any programming language, helping developers control the flow of execution. Python has three fundamental types of control structures: Sequence, Selection, and Repetition (Looping). Let’s explore each with examples. [1]

1. Sequence Structure

The sequence structure is the simplest control structure where statements execute one after another in the order they are written.

Example:

print("Step 1: Start the program")
print("Step 2: Process data")
print("Step 3: End the program")

Output:

Step 1: Start the program
Step 2: Process data
Step 3: End the program

In this example, each statement executes sequentially from top to bottom.

2. Selection (Decision-Making) Structure

The selection structure allows the program to make decisions based on conditions. In Python, we use if, if-else, and if-elif-else statements for decision-making.

Example:

age = int(input("Enter your age: "))
if age >= 18:
    print("You are eligible to vote.")
else:
    print("You are not eligible to vote.")

Output (if input is 20):

You are eligible to vote.

Output (if input is 15):

You are not eligible to vote.

The program checks the condition and selects a path accordingly.

3. Repetition (Looping) Structure

Repetition structures allow executing a block of code multiple times. Python supports two types of loops: for and while.

Example 1: Using for loop

for i in range(1, 6):
    print("Iteration", i)

Output:

Iteration 1
Iteration 2
Iteration 3
Iteration 4
Iteration 5

Example 2: Using while loop

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

Output:

Count is 1
Count is 2
Count is 3
Count is 4
Count is 5

The while loop continues executing until the condition count <= 5 becomes false.

Conclusion

Understanding control structures is crucial for writing efficient programs. Python provides three main types of control structures:

1. Sequence – Executes statements in order.
2. Selection – Makes decisions using if statements.
3. Repetition – Repeats code using loops (for and while).

Further Learning

• Flow Control Statements in Python

References

• [1] What are control flow statements in Python? - educative.io