THEORETICAL RECAP A list (also called an array or table) is an ordered collection of values stored under a single name, where each element occupies a position identified by an index. In most programming languages, indexing starts at 0: the first elem...

Until now, you have worked with variables that store a single value at a time: a number, a text string, or a boolean. But real programs often need to handle many values at once. Imagine you want to store the names of thirty students, the prices of on...

Documentation and comments are two closely related practices that make your code understandable, maintainable, and reusable by yourself and by others. After learning to write loops, conditions, and functions, you now need to learn how to explain what...

THEORETICAL RECAP A factorial of a non-negative integer n (written n!) is the product of all positive integers from 1 up to n, with the special rule that 0! equals 1. In programming, the factorial is the classic example used to compare two approaches...

In the previous chapters, you learned to create functions and procedures to organize your code into reusable blocks. Now we go deeper into two fundamental concepts that determine how functions communicate with the rest of the program: the passage of ...

THEORETICAL RECAP A function is a reusable block of code that takes zero or more inputs (called parameters or arguments), performs a task, and often returns a result. The mental model to keep in mind is that of a machine: you feed it raw material (th...

Until now, you have written instructions in a single continuous block: conditions, loops, calculations, all following one another from top to bottom. This works for small exercises, but as soon as a program grows, this approach becomes unmanageable. ...

THEORETICAL RECAP A loop repeats a block of instructions until a condition is met. You have already worked with 'while' loops (repeat as long as a condition is true) and 'for' loops (repeat a known number of times, with a counter). The mental model t...

Nested loops are one of the most powerful tools in programming, but also one of the most dangerous in terms of performance. A nested loop is simply a loop placed inside another loop. You already know how to write a single loop (the 'while' and 'for' ...

THEORETICAL RECAP A factorial of a non-negative integer N, written N!, is the product of all positive integers from 1 up to N. For example, 5! = 5 × 4 × 3 × 2 × 1 = 120. By convention, 0! = 1. This is a perfect problem for the 'for' loop, because you...