Loops in Python: what should you know about them?


Redacción Tokio | 17/02/2023

In programming contexts, loops exist in all languages as a concept. They’re a tool that makes it easier for programs to implement iterations. Simply explained, loops in Python and in most programming languages are used to execute the same block of code twice or more times.

Loops are typically existing functions in all programming languages and provide similar basic functionality, but their implementation and syntax varies depending on the code. In this article we are going to focus on what loops are, what types are there and what loops in Python are.

Python is currently the fifth most used programming language globally. Widely used in Big Data, Artificial Intelligence and Machine Learning, it also has many back-end applications for web development.

In this context, Python does not stop growing and programmers that are experienced in using this language are increasingly demanded by companies. Therefore, training with a Python Programming Course can help improve your job prospects.


What are loops in Python?

In Python, the code is executed sequentially. In other words, if what has been programmed is made up of several lines, the execution of what has been programmed will begin with the first, go on to the second, and so on.

However, there are cases in which this is not ideal, even if it’s necessary that a certain block is repeated. In which cases is this necessary? We will detail this later, but the usual thing is that a certain condition needs to be met. Thanks to the loops in Python, it’s possible to make these code fragments iterate in the execution of the program.

There are different types of loops in programming. While other languages present up to three different types of loops, Python has two fundamental types of loops:

‘For’ Loops

‘For’ loops are based on iterators that go through all the elements of objects that are iterable: lists, tuples, strings. They execute a piece of code repeatedly based on the number of elements contained in the iterable object.


‘While’ Loops

‘While loops’ execute blocks of code that they affect as long as the condition of the loop is true. The ‘while’ loop repeats until the condition has been met a specified number of times.

Even if this is similar to if functions, the ‘while’ loop in Python is executed multiple times, while the if is only executed once.


How to loop in Python

Both in the case of for loops and while loops, execution occurs when the condition that has been defined is true. If it is false, the loop does not execute, while if it is true, it iterates and the code block is repeated a certain number of times:

  • Start: the loop starts in Python with for<elem> in <iterable>: <code block> or While (condition): expression (block of code).
  • Condition: if the condition is true, the code block is iterated and executed again. If it is false, the program continues with an ordinary sequential execution.

Once the loop has been executed, it will continue until the condition declared in the code is false. At that time, the program will continue to run sequentially.

Another important feature about how loops in Python work is that both ‘for’ and ‘while’ loops can work as nested loops. What are nested loops in Python? Basically, this term refers to using one or more loops inside another loop. That is, several loops are combined into one to solve complex problems during the development of the program.


How to create loops in Python

As we said, Python presents two types of loops, each of them with its own syntax and created in different ways:

  • ‘While’ loops are created with this syntax: While (condition): expression (block of code). The expression must be checked since the expression becomes true when the loop is executed. On each iteration of the loop, that expression will be checked. When it is false, the loop will end.
  • ‘For’ loops are created like this: for<elem> in <iterable>: <code block>. In this case, elem refers to the variable from which the iterator starts, while the iterable is the element on which the variable applies the loop. The loop will repeat until all the values in the sequence of elements of the iterable are completed.

Also, loops in Python can be controlled. For this, the following expressions are used:

  • Break: this ends the loop, breaks it.
  • Continue: this skips all the code below and returns to the start of the loop.

In case the breaking of the loops in Python is not properly indicated, an infinite loop is created. That is, the program continually executes the same piece of code. This may be an error, but infinite loops may be programmed for specific purposes.


Get trained as a Python programmer!

Loops in Python are key to being able to develop and implement certain functionalities in programs created using this language. A feature that you must not only know, but master in order to work as a programmer.

For this, it is best to find a quality training option. A course that turns you into a true programming samurai and an expert in programming in one of the most important languages today. Interested?

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