Python 101: Mastering Conditional Statements and Loops

Python 101: Mastering Conditional Statements and Loops

Whether you want to make decisions based on specific conditions or repeat actions until a task is complete, understanding conditional statements and loops proves to be a crucial part for writing efficient and dynamic code in python. In this article, we'll explore the core concepts of conditional statements and loops "the building blocks that empower you to control the flow of your Python programs." We’ll also break down each type of conditional statement and loop with clear examples, so you can easily follow along.

Understanding Conditional Statements in Python

Imagine you're giving instructions to someone. 

Let's say: "If it's raining, you will say- take an umbrella" or  "if it's sunny, you will say - wear sunglasses." This is exactly how conditional statements work in programming. In other words they simply allow your code to make decisions based on the conditions they meet.

What are Conditional Statements?

Conditional statements in Python let your program decide which code to run based on whether something is true or false. The main types are if, elif (else if), and else.

How Conditional Statements Work

1. if statement: Tells the program to do something only if a specific condition is true.
2. elif statement: Allows checking multiple conditions one by one.
3. else statement: Runs a block of code if all previous conditions are false.

Basic Syntax of Conditional Statements

if condition1:
    # Code to execute if condition1 is true
elif condition2:
    # Code to execute if condition2 is true
else:
    # Code to execute if all conditions are false

Example

Let's say we want to decide what to print based on a person's age:

age = 18

if age < 18:
    print("You are a minor.")
elif age == 18:
    print("You just became an adult!")
else:
    print("You are an adult.")

For this example, we start with a variable age set to 18. Here we used if, elif, and else statements to decide what message should be print based on the value of age. This way, the program provides a message based on the person's age.

Here: 

• If the age is less than 18, then the output will print "You are a minor."
• If age equals 18, then the output will print  "You just became an adult!"
• Otherwise, then the output will print  "You are an adult."

Introduction to Loops in Python

Loops are like automated to-do lists for your code. They repeat a block of code multiple times until a condition is met, saving you from writing repetitive tasks.

What are Loops?

Loops help you execute the same piece of code multiple times. Python provides two main types of loops:

• for loop: Used to iterate over a sequence (like a list or a string).
• while loop: Repeats as long as a specified condition is true.

For Loop 

The for loop in Python is used to repeat a set of actions for every item in a list, string, or range of numbers. It makes it easy to do something multiple times, like adding up numbers or printing each letter in a word. Let’s see how for loops work with a few easy examples.

Basic Syntax of for Loop

for item in sequence:
    # Code to execute for each item

Example

Let's try to print the names of different fruits using 'for' loop in python:

fruits = ["apple", "banana", "cherry", "peaches"]

for fruit in fruits:
    print(fruit)

Here, we have a list of fruits: ["apple", "banana", "cherry", "peaches"]. We use a for loop to go through each fruit in the list. For each fruit, the loop prints its name. This means the program will print each fruit in the list one by one: first "apple," then "banana," followed by "cherry," and finally "peaches."

Output

apple
banana
cherry
peaches

While Loop

The while loop in Python repeats a set of actions as long as a certain condition is met. It’s useful when we don’t know in advance how many times we need to repeat something. For example, we can use a while loop to keep asking for user input until they enter the correct answer. Let’s try to understand it with some examples.

Basic Syntax of While Loop

while condition:
    # Code to execute as long as the condition is true

Example

Let's say we want to keep printing numbers until we reach 5 using while loop:

count = 0

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

In this example, we start with a variable count set to 0. We use a while loop to keep running the code inside it as long as count is less than 5. Each time the loop runs, it prints the current value of count and then adds 1 to count. This process continues until count reaches 5. When count becomes 5, the condition count < 5 is no longer true, so the loop stops.

Output

Count is: 0
Count is: 1
Count is: 2
Count is: 3
Count is: 4

Mixing Conditional Statements with Loops

Combining conditional statements with loops can help you unlock even more powerful capabilities in Python. By mixing if statements with for and while loops, you can create complex logic that checks conditions and performs actions repeatedly until a certain criteria is met. This combination allows us to tackle a wide range of programming challenges, from processing data to building interactive applications. 

Example

Let's say we want to check if the numbers in a list are even or odd:

numbers = [1, 2, 3, 4, 5]

for number in numbers:
    if number % 2 == 0:
        print(f"{number} is even.")
    else:
        print(f"{number} is odd.")

Here, we have a list of numbers: [1, 2, 3, 4, 5]. We use a for loop to go through each number in the list one by one. For each number, we check if it is even or odd using an if statement. If the number divided by 2 has no remainder (number % 2 == 0), it's even, so we print that it is even. If there is a remainder, the number is odd, and we print that it is odd. This way, the program will tell us whether each number in the list is even or odd.

Output

1 is odd.
2 is even.
3 is odd.
4 is even.
5 is odd.

Using break and continue in Loops

In Python, break and continue in loops offer powerful ways to control the flow of program execution. The break statement allows us to exit a loop prematurely when a certain condition is met, while the continue statement skips the rest of the current loop iteration and moves to the next one. Understanding how to use these statements effectively can help us manage complex looping scenarios and make our code more efficient. 

Let’s explore how break and continue work with some practical examples.

• break: Exits the loop entirely when a certain condition is met.
• continue: Skips the current iteration and continues with the next one.

Example (break)

for number in range(1, 6):
    if number == 3:
        break
    print(number)

In this example, we use a for loop to iterate through numbers from 1 to 5, generated by range(1, 6). For each number, the loop checks if it is equal to 3. When the number is 3, the break statement is triggered, which immediately stops the loop. As a result, only the numbers 1 and 2 are printed before the loop ends. Once the loop encounters the number 3, it exits and does not print any numbers beyond that.

Output

1
2

Example (continue)

for number in range(1, 6):
    if number == 3:
        continue
    print(number)

In this example, we use a for loop to go through numbers from 1 to 5, provided by range(1, 6). For each number, the loop checks if it is equal to 3. When the number is 3, the continue statement is triggered, which skips the rest of the current iteration and moves to the next number in the loop. As a result, the number 3 is not printed, but the numbers 1, 2, 4, and 5 are printed.

Output

1
2
4
5

Conclusion

Today, we delved into the core concepts of conditional statements and loops in Python—two crucial elements that make our code more intelligent and adaptive. By learning how to use if, else, and elif statements, along with for loops, while loops and break and continue conditions, we learned to develop dynamic and versatile code that efficiently handles a variety of scenarios. Also, while mastering these tools puts you on the path to becoming a skilled Python programmer, one must always keep in mind that the key to grasping these concepts is practice. So, continue experimenting and discover what works best for your coding needs.

Thanks for Scrolling… 😄

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