Flowcharts

Flowcharts are visual representations of steps in an algorithm. An algorithm is a set of instructions that solve a problem, and a computer program is an implementation of an algorithm.

There are four main flowchart symbols: an oval for start/end, a rectangle for a process, a parallelogram for input/output, and a diamond for decisions. Decisions should ideally be binary questions with two possible outcomes (yes/no or true/false).

An example flowchart illustrates a user login process: checking if an account exists, signing up if not, entering username and password, verifying details, and looping back if details are incorrect. It also demonstrates how to loop back to repeat steps and the importance of arrows indicating direction.

A rectangle with additional lines inside (a subroutine symbol) can represent a separate program or a more complex process like a 'sign up screen'. This helps break down large flowcharts into smaller, more manageable parts.

An example of a 'sign up screen' subroutine flowchart is provided, showing steps like entering username and password, checking if the user already exists, and saving details to a database. This further demonstrates how complex processes can be organized using subroutines.