🧮 BASIC Interpreter in C++

Welcome to your very own retro computing adventure! This project is a minimalist interpreter for our own BASIC dialect, a simplified version of the BASIC programming language originally designed for early microcomputers. Written in modern C++, this interpreter brings vintage programming charm to today's systems.

🚀 Features

• 📝 Line-numbered program input
• 🔤 Single-letter variables (A to Z)
• 📤 Basic I/O: PRINT, INPUT
• 🔁 Control flow: IF, GOTO, GOSUB, RETURN
• 💬 Comments via REM
• 🧠 In-memory program storage and execution
• 🧪 Interactive REPL (Read-Eval-Print Loop)

📦 Getting Started

Requirements

• C++17 or later
• A standard C++ compiler (e.g., g++, clang++, MSVC)
• Google test

Build Instructions

git clone https://github.com/rossonlinesolutions/BASIC.git
cd BASIC
make
./build/basic

Or compile manually:

g++ -std=c++17 -o basic -Iinclude src/Main.cpp

🧑‍💻 Usage

Once launched, you'll enter the REPL. You can type Tiny BASIC commands directly or enter a full program line-by-line using line numbers.

📃 Example

A simple sorting algorithm example:

REM "Read 24 ascii characters"

LET A = 2
20 IF A = 26 THEN GOTO 100
INPUT VAR(A)
LET A = A + 1
GOTO 20

100 REM "Sorting..."

LET A = 2

REM "If reached end, everything is sorted."
110 IF A = 25 THEN GOTO 200
LET A = A + 1
IF VAR(A - 1) <= VAR(A) THEN GOTO 110

REM "Swap A-1"
LET B = VAR(A - 1)
LET VAR(A - 1) = VAR(A)
LET VAR(A) = B

REM "Restart from new"
LET A = 2
GOTO 110

200 REM "Print all variables in ascending order"
LET A = 2

210 IF A = 26 THEN END
PRINT VAR(A)
LET A = A + 1
GOTO 210

REM "Start execution:"
RUN

📚 Language Reference

Command	Description
LET	Assign value to variable
PRINT	Display a string or character sequences
INPUT	Read user input
IF ... THEN	Conditional execution
GOTO	Jump to a line number
GOSUB/RETURN	Subroutine call/return
REM	Comment
END	Terminate program

See the Language Specification for full language reference.

📜 License

This project is licensed under the MIT License. See LICENSE for details.