Tutorial How to Use Loop in Python: For, For In, For with List, Do, While, When, Each

Welcome to our tutorial on loops in Python! As programmers, we often encounter tasks that require us to perform the same operation multiple times. This is where loops come in handy. With loops, we can repeat a block of code a specific number of times or until a certain condition is met. In this tutorial, we will explore various loop types in Python, such as for, for…in, for with list, do, while, when, and each.

By the end of this tutorial, you will have a solid understanding of how to effectively use loops in Python. So let’s dive into the world of loops and enhance our coding skills!

Introduction to Loops in Python

In programming, loops allow us to repeat code multiple times, making them a crucial concept for any programmer to understand. In Python, there are several types of loops that cater to different scenarios, making them a versatile tool in your coding arsenal. Let’s take a look at the different loop types and how to use them effectively.

What is Looping?

Looping, or iteration, is a process that repeats a certain block of code until a specific condition is met. This can come in handy when you need to perform an action multiple times, or when you want to iterate over the elements in a data structure, such as a list or a dictionary.

Different Types of Loops in Python

Python provides several loop types for different situations:

Each loop type has its own syntax and usage, and we will explore them in more detail throughout this tutorial.

The For Loop

The for loop is an essential loop in Python that allows us to iterate over a sequence or other iterable objects. It is particularly useful when you need to perform a set of instructions for each element in the sequence. The syntax for a for loop is:

Here is an example of a for loop that iterates over a list of fruits and prints each one:

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

The output of this code would be:

apple
banana
cherry

The for loop can also be used with other iterable objects such as tuples, strings, and ranges.

With this basic knowledge of the for loop, we can move on to our next section to explore the for…in loop and the for loop with list in more detail.

The For…In Loop and For Loop with List

Another variation of the for loop is the for…in loop, which is specifically designed to iterate over the items of a sequence. It is also commonly used to iterate over the elements of a list.

The syntax for the for…in loop is as follows:

Let’s look at an example:

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

In this example, we have a list of fruits, and we are using the for…in loop to iterate over each fruit and print it to the console. The output of this code would be:

apple
banana
cherry

Another way to use the for loop with a list is by using the range() function. This allows us to loop through a range of numbers and perform a set of instructions for each number.

The syntax for the for loop with range() is as follows:

Here’s an example:

for x in range(6):
    print(x)

In this example, we are using the for loop with range() to print the numbers 0 to 5 to the console.

Both the for…in loop and the for loop with range() are powerful tools that allow us to perform a set of instructions on each element of a list or a range of numbers. They are highly versatile and commonly used in Python programming.

The Do and While Loops

In addition to the for loop, Python also provides two other loop types: the do loop and the while loop. The do loop is useful when you want to execute a block of code at least once before checking if the condition is true, while the while loop is ideal when you want to execute a block of code repeatedly as long as a specific condition is true.

The Do Loop

Let’s start by looking at the syntax of the do loop:

Here’s an example of a do loop:

i = 0
do:
  print(i)
  i += 1
while i <= 5

This code block will print the values of i from 0 to 5.

The While Loop

The while loop, on the other hand, repeatedly executes a block of code while a specific condition remains true. Here’s the syntax of the while loop:

Here’s an example of a while loop:

i = 0
while i <= 5:
  print(i)
  i += 1

This code block will also print the values of i from 0 to 5. It’s important to note that if the condition in the while loop is never met, the loop will continue indefinitely and your program may freeze. Therefore, it’s crucial to ensure that the condition will eventually be false.

The When Loop and Each Loop

In addition to the traditional loop types, Python offers two more loop types: the when loop and the each loop. These loops are useful when you need more flexibility in certain scenarios.

The When Loop

The when loop is used to execute a block of code when a specific condition is met. It is similar to the if statement, but it allows you to repeat the same block of code multiple times until the condition is no longer true.

Here is the syntax for the when loop:

Here is an example of using the when loop:

num = 0

when num < 5 do
  print("Number is", num)
  num += 1
end

This code will print out the numbers from 0 to 4.

The Each Loop

The each loop is used to iterate over key-value pairs in a dictionary or items in any iterable object. It allows you to perform a set of instructions for each element in the object.

Here is the syntax for the each loop:

Here is an example of using the each loop:

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

each fruit in fruits do
  print(fruit)
end

This code will print out the following:

apple
banana
cherry

As you can see, the each loop allows you to easily iterate over all items in a list or any iterable object.

Conclusion

By mastering various loop types in Python, we have expanded our coding skills and unlocked new possibilities in our programming journey. Throughout this tutorial, we explored the different loop types in Python, including the for, for…in, for with list, do, while, when, and each loops.

We learned that loops are an important concept in programming that allow us to repeat a certain block of code multiple times, and that Python provides a variety of loop types catered to different scenarios. Whether we need to iterate over all elements in a list, perform a set of instructions a specific number of times, or execute a block of code until a certain condition is met, Python has got us covered.

By practicing and experimenting with the different loop types, we can gain hands-on experience and become more proficient in using loops effectively. So, let’s continue to enhance our coding skills and explore the endless possibilities that loops can offer in our Python programs. Happy coding!