List of Contents:
- INTRODUCTION
- What are Control Statements?
- Conditional Statements
- Looping Statements
- Jump Statements
- Combining Control Statements
- Best Practices
- Conclusion
INTRODUCTION
Python is one of the most popular programming languages today, known for its simplicity and versatility. A key concept in Python programming is control statements, which allow developers to control the flow of their programs.
Whether a beginner or an experienced developer, understanding control statements is fundamental to writing efficient, clean, and functional code.
In this article, we will dive deep into the types of control statements in Python, explain their usage, and demonstrate their functionality with practical examples.
What Are Control Statements?
Control statements in Python allow you to dictate how and when certain code blocks are executed. These statements enable conditional execution, loops, and early exits from loops or functions.
Python provides three primary types of control statements:
- Conditional Statements: if, if-else. if – elif-else
- Looping Statements: while for
- Jump Statements: break, continue and pass
Let’s break each of these down with examples.
1. Conditional Statements: Making Decisions
Conditional statements let you execute code based on certain conditions. These include if, if -else and if – elif – else .
1.1 if
The if statement checks a condition, and if the condition is True, it executes the block of code indented under it.
age = 18
if age >= 18:
print("You are eligible to vote.")In the above example, since age is 18, the condition evaluates to True, and the message is printed.
1.2 if – else
The else statement executes when none if conditions return false.
number = 5
if number > 10:
print("Greater than 10")
else:
print("10 or less")1.3 if – elif – else
The elif statement (short for “else if”) allows us to check multiple conditions sequentially.
score = 75
if score >= 90:
print("Grade: A")
elif score >= 75:
print("Grade: B")
else:
print("Grade: C")Here, the program evaluates each condition in sequence and executes the block of the first condition that is True .
1.4 Nested Conditional Statements
You can nest if statements within each other for more complex decision-making.
age = 25
citizen = True
if age >= 18:
if citizen:
print("You are eligible to vote.")
else:
print("You are not eligible to vote")2. Looping Statements: Repeating Actions
Looping statements allow you to execute a block of code multiple times.
2.1 for Loop
The for loop is used to iterate over a sequence like a list, tuple, or string.
fruits = ["apple", "banana", "cherry"]
for fruit in fruits:
print(f"I love {fruit}")Output:
I love apple
I love banana
I love cherry
One can also use the range() function to generate a sequence of numbers.
for i in range(1, 6):
print(f"Square of {i} is {i ** 2}")Output:
Square of 1 is 1
Square of 2 is 4
Square of 3 is 9
Square of 4 is 16
Square of 5 is 25
2.2 while Loop
The while loop continues executing as long as its condition remains True.
count = 0
while count < 5:
print(f"Count is {count}")
count += 1Output:
Count is 0
Count is 1
Count is 2
Count is 3
Count is 4
Be cautious with while loops to avoid infinite loops by ensuring the condition eventually becomes False.
3. Jump Statements: Controlling Loop Execution
Jump statements let you alter the flow of loops by exiting them early or skipping iterations.
3.1 break Statement
The break statement exits the loop prematurely.
for number in range(10):
if number == 5:
print("Stopping the loop.")
break
print(number)0
1
2
3
4
Stopping the loop.
3.2 continue Statement
The continue statement skips the rest of the current iteration and moves to the next iteration.
for number in range(5):
if number == 3:
continue
print(number)Output:
0
1
2
4
3.3 pass Statement
The pass statement does nothing and is a placeholder for code that will be added later.
for number in range(5):
if number == 2:
pass # Code to be added later
print(number)3.4 Combining Control Statements
Control statements can be combined for complex logic.
scores = [85, 62, 90, 45, 77]
for score in scores:
if score < 50:
print(f"Score {score}: Failed")
continue
elif score >= 85:
print(f"Score {score}: Excellent")
else:
print(f"Score {score}: Passed")Output:
Score 85: Excellent
Score 62: Passed
Score 90: Excellent
Score 45: Failed
Score 77: Passed
Simple Calculator
Control statements can power basic applications like calculators.
operation = input("Enter operation (add, subtract, multiply, divide): ").lower()
a = int(input("Enter first number: "))
b = int(input("Enter second number: "))
if operation == "add":
print(f"Result: {a + b}")
elif operation == "subtract":
print(f"Result: {a - b}")
elif operation == "multiply":
print(f"Result: {a * b}")
elif operation == "divide":
if b != 0:
print(f"Result: {a / b}")
else:
print("Error: Cannot divide by zero.")
else:
print("Invalid operation.")Output:
Enter operation (add, subtract, multiply, divide): multiply Enter first number: 10
Enter second number: 5
Result: 50
Filtering Data
Control statements are useful in data processing.
data = [15, 23, 7, 18, 42, 30]
filtered_data = []
for num in data:
if num % 2 == 0:
filtered_data.append(num)
print("Filtered even numbers:", filtered_data) #output: Filtered even numbers: [18, 42, 30]
Best Practices
- Keep it simple: Write clear and concise conditions.
- Use comments: Document complex logic.
- Avoid deeply nested loops
- Debug with print statements
Conclusion
Control statements are a cornerstone of Python programming. Mastering these constructs enables you to write dynamic, efficient, and elegant code. Whether you’re building simple scripts or complex applications, understanding how to control the flow of your program is essential.
Practice regularly, experiment with different examples, and incorporate control statements into your projects. Happy coding!
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