Learning Python syntax is one thing.
Using variables, conditionals, loops, lists, dictionaries, and functions together to build an actual program is where things start to become much more interesting.
I published a new step-by-step project in TuCodigoCotidiano where we build a personal expense tracker that runs entirely in the terminal.
The guide is written in Spanish and is designed for people who already know the basic Python concepts but want to understand how those pieces fit together inside a real application.
What we build
The project starts small.
A single expense becomes a dictionary.
Multiple expenses become a list of dictionaries.
Then we gradually add functions until the program can:
- Register income
- Register expenses
- Display transactions
- Calculate total income
- Calculate total expenses
- Calculate the current balance
- Group expenses by category
- Validate user input
- Run through an interactive terminal menu
- Save data to JSON
- Load previous data when the program starts again
The final structure is intentionally simple:
problem → data → functions → interaction → validation → persistence → application
No classes.
No database.
No external libraries.
Just Python and the standard library.
Why I built the tutorial this way
A common beginner experience is learning concepts independently:
if
for
lists
dictionaries
functions
But knowing those concepts does not automatically explain how to design a program.
So instead of starting with a large finished script, the project begins with a practical question:
What would a program need to do to help you understand where your money is going?
From there, every new piece of code solves one specific part of the problem.
The goal is not only to finish an expense tracker.
The goal is to understand how a real program grows from a simple idea.
Read the complete project
🐍 Construye un gestor de gastos personales en la terminal
The complete tutorial is in Spanish and includes the code, explanations, visual diagrams, validation, JSON persistence, testing ideas, common mistakes, and challenges to extend the project.
If you were extending this project, what would you build next: budgets, dates, search, editing transactions, or something else?
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