1. Introduction:

In the previous posts, we’ve covered the basics of Python, including variables, data types, and operators. Now it’s time to learn how to control the flow of your program. This means making decisions based on conditions (using if statements) and repeating actions multiple times (using loops).

In this post, we’ll explore the two most important aspects of control flow in Python: conditional statements and loops. These are essential tools for building more interactive and dynamic Python programs.

2. Conditional Statements (if, elif, else):

Conditional statements allow you to execute code based on whether a certain condition is true or false. Python’s if, elif, and else statements are used for this purpose.

• if statement: Executes a block of code if the condition is true.
• elif statement: Checks another condition if the previous if condition was false.
• else statement: Executes a block of code if none of the previous conditions are true.

Example:

age = 20 if age >= 18: print("You are an adult.") else: print("You are a minor.")

You can also chain multiple conditions with elif:

age = 15 if age >= 18: print("You are an adult.") elif age >= 13: print("You are a teenager.") else: print("You are a child.")

3. Logical Operators in Conditional Statements:

Logical operators like and, or, and not can be used in conditional statements to combine multiple conditions.

Example:

age = 20 has_ticket = True if age >= 18 and has_ticket: print("You can enter the concert.") else: print("You cannot enter the concert.")

4. Loops – Repeating Actions:

Loops allow you to repeat a block of code multiple times, which is very useful when working with lists, ranges, or other repetitive tasks.

4.1 For Loop:

The for loop is commonly used to iterate over a sequence (such as a list, tuple, or range).

Example – Iterating through a list:

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

Example – Using a range() function:

for i in range(5): # This will iterate over numbers 0 to 4 print(i)

You can also specify a starting point, ending point, and step in range():

for i in range(1, 10, 2): # Starts from 1, goes up to 9, and increments by 2 print(i)

4.2 While Loop:

The while loop repeatedly executes a block of code as long as a condition is true.

Example:

count = 0 while count < 5: print(count) count += 1 # Increment the counter to avoid an infinite loop

4.3 Breaking and Continuing Loops:

Sometimes, you may want to exit a loop early or skip the current iteration. This is where break and continue come in handy.

• break: Exits the loop immediately.
• continue: Skips the current iteration and moves to the next one.

Example – Using break:

for i in range(10): if i == 5: break # Exit the loop when i equals 5 print(i)

Example – Using continue:

for i in range(10): if i % 2 == 0: continue # Skip even numbers print(i)

5. Nested Loops:

You can nest loops inside one another. This is useful when working with multi-dimensional data (like lists of lists).

Example:

matrix = [ [1, 2, 3], [4, 5, 6], [7, 8, 9] ] for row in matrix: for element in row: print(element, end=" ") print() # Print a new line after each row

6. Conclusion:

Control flow is a key concept in programming that allows you to make decisions and repeat actions based on conditions. By mastering if statements, for loops, while loops, and control flow modifiers like break and continue, you’ll be able to write more complex and interactive Python programs.

In the next blog post, we’ll dive into functions, which allow you to organize and reuse your code more effectively. Stay tuned for more Python tips and tricks!