Lightweight BASIC interpreter written in standard C in dual files. Aimed to be embeddable, extendable and portable.
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Copyright (C) 2011 - 2019 Wang Renxin

Build status MIT license

Web playground



MY-BASIC is a lightweight BASIC interpreter written in standard C in dual files. It's aimed to be embeddable, extendable and portable. It is a dynamic typed programming language, reserves structured syntax, supports a style of prototype-based programming (OOP), also implements a functional paradigm by lambda abstraction. The core is written in a C source file and an associated header file. It's easy to either use it as a standalone interpreter or embed it with existing projects in C, C++, Java, Objective-C, Swift, C#, etc. and totally customizable by adding your own scripting interfaces.

Main features

MY-BASIC offers a wide range of features including:

  • Written in standard C, source code is portable to a dozen of platforms
  • Lightweight (within less than 128KB footprint), fast, and configurable
  • With both retro and modern BASIC syntax
  • Case-insensitive tokenization, and many other indelible BASIC flavour
  • Unicode support
  • Prototype-based programming, with reflection support
  • Lambda abstraction enhanced functional programming
  • Customizable referenced/non-referenced usertype
  • Collection construction and manipulation functions for LIST and DICT
  • Automatic releasing for referenced values (prototype, lambda, referenced usertype, list, dictionary, etc.) benefited from reference counting and garbage collection
  • Common numeric and string functions
  • Structured sub routine definition with the DEF/ENDDEF statements
  • Reserved retro GOTO, GOSUB/RETURN
  • Importing multiple source files with the IMPORT statement
  • Debug API
  • Customizable memory pool
  • Easy API, for extending new BASIC functions
  • Easy interacting BASIC facilities at native side, and vice versa
  • More features under development


Get BASIC8 - the fantasy computer powered by MY-BASIC - on Steam for game and other program development in an integrated environment.

See awesome user creations.

BASIC at a glance

A "Hello World" convention in MY-BASIC:

input "What is your name: ", n$

def greeting(a, b)
	return a + " " + b + " by " + n$ + "."

print greeting("Hello", "world");

Read the MY-BASIC Quick Reference to get details about how to program in MY-BASIC.


Using standalone interpreter binary

This repository contains precompiled binaries for Windows and macOS, the easiest way is to download to get a direct playground. Or you can make a build by:

  • Using the Visual Studio workspace my_basic.sln on Windows to build an executable
  • Using the Xcode workspace my_basic_mac.xcodeproj on macOS to build an executable
  • Using the makefile on *nix OS to build an executable

Follow these steps to compile an interpreter binary manually for any platform:

  1. Retrieve everything under the core and shell folders for a minimum build
  2. Setup your toolchain for compiling and linking
  3. Compile core/my_basic.c and shell/main.c, with both including core/my_basic.h; then link up an executable

The standalone interpreter supports three running modes:

  • Execute the binary without arguments to use the interactive mode
    • Type "HELP" and hint Enter to get usages of it
  • Pass a file to the binary to load and run that BASIC source code
  • Pass an argument -e followed with an expression to evaluate and print instantly as a simple calculator, eg. -e "2 * (3 + 4)"

Combining with existing projects

Just copy core/my_basic.c and core/my_basic.h to your project and add them to the build configuration. You can link with MY-BASIC as a lib as well.

For details about using MY-BASIC after integration, see MY-BASIC Quick Reference and read the Wiki pages.

Interpreter workflow diagram

It's recommended to know the basic principle of MY-BASIC before customizing; nothing's better than a workflow diagram to get a first image.

A simple setup as follow:

#include "my_basic.h"

int main() {
	struct mb_interpreter_t* bas = NULL;

	mb_load_string(bas, "print 22 / 7;", true);
	mb_run(bas, true);

	return 0;


The manual explains most of the fundamental topics, however it doesn't cover everything; read the Wiki as supplement instructions, such as machinism behind MY-BASIC, efficient practice, etc:


List of donors.

Consider supporting MY-BASIC development with a donation if you like this project.

One-off donation via PayPal.