Introduction

In programming, loops are fundamental constructs that allow you to repeat a block of code multiple times without having to write it out repeatedly. They are essential for automating repetitive tasks, iterating over data structures like lists or arrays, and performing operations until a specific condition is met.

Loops save time, reduce errors, and make your code more efficient and readable. In Python, there are two primary types of loops: the for loop and the while loop.

Why Use Loops?

  • Efficiency: Loops reduce the need for redundant code, allowing you to perform repetitive tasks more efficiently.
  • Automation: They automate tasks by repeating actions until a certain condition is met.

For-loop

Useful if your computation needs the same sequential workflow for different variables or subsets.

# Pseudocode
for <iteration variable> in <control vector>:
    # do something using the iteration variable

While-loop

Useful if your computation needs the same sequential workflow for a variable or subsets but you only know how often it is needed when the loop is already running.

# Pseudocode
while <some logical expression with iteration variable>:
    # do something using iteration variable and update it

What loop to choose?

One rule for choosing between a while- and a for-loop is that while-loops are used when the number of iterations is unknown and for-loops are used when the number is known.

Let’s go through a few examples of each:

  • Use a for-loop to iterate over an array.
  • Use a for-loop when you know the loop should execute n times.
  • Use a while-loop for reading a file into a variable.
  • Use a while-loop when asking for user input.
  • Use a while-loop when the increment value is nonstandard.

Importance of Indentation in Python

Indentation is crucial in Python because it determines the structure and flow of the code. Unlike many other programming languages that use braces or keywords to define code blocks, Python uses indentation to group statements.

How Indentation Works:

  1. Each level of indentation should be consistent (typically 4 spaces).
  2. All statements within the same block should be indented to the same level (e.g things that should happen if and if-statement is True).
  3. The end of the indentation signifies the end of the code block.

Updated: