LabelBASIC

A lightweight BASIC interpreter for learning and scripting. Simple, expressive, and fun.

LabelBASIC executes programs line-by-line directly from source—no compilation step. Write code in your favorite text editor (.lbas files) and run it immediately. It's an interpreter that brings back the joy of BASIC without the line-number cruft.

What Can You Do?

• Calculate and transform data with clean, readable syntax
• Process files line-by-line or interactively
• Build small scripts quickly—no boilerplate
• Learn programming fundamentals in a forgiving environment
• Resurrect classic BASIC programs from vintage books and archives

Key Features

• Label-based flow control: Replace line numbers with meaningful labels. Jump with GOTO and call subroutines with CALL
• Loop constructs: DO/NEXT loops with optional WHILE and UNTIL clauses
• Conditional branching: IF/THEN/ELSE statements
• Variables and arrays: String and numeric variables, plus 1D and 2D arrays
• Built-in functions: Math (sin, cos, tan, rnd), string operations ($chr, $str, $front, $back, $join), and more
• File and terminal I/O: OPEN, ASK, PRINT with output redirection
• Terminal graphics: XTEND keyword for ANSI color and cursor control
• Pre-processor support: Use #include to add function libraries (like math.h)
• Recent features: ELSE keyword and nocr() to suppress newlines on print output

Quick Example

; Calculate average of user input
Begin:
    Let sum = 0
    Let num = 0
    Do
        Ask "Enter a number (0 to stop): ", data
        Break if data == 0
        Let sum = sum + data
        Let num = num + 1
    Next
    Print "Average: ", sum / num
    Stop

Running LabelBASIC

lb your_program.lbas

Documentation

See the included User Manual for detailed syntax, all keywords, operators, functions, and examples—including how to convert vintage line-numbered BASIC programs.

Design Philosophy

LabelBASIC is deliberately simple: it focuses on readability and immediate execution. No complex type systems, no module overhead, no build pipeline. Just code and results.

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A modern take on a classic language.