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VARPTR

Implementation Note

⚠️ Not Implemented: This feature requires direct memory access and is not implemented in this Python-based interpreter.

Behavior: Function is not available (runtime error when called)

Why: In the original MBASIC, VARPTR returned a pointer to the variable's memory address. Python uses managed memory with garbage collection, so variables don't have fixed memory addresses.

Historical Context: VARPTR was used to pass variable addresses to assembly language subroutines via CALL or USR functions, which are also not implemented.

Historical Reference: The documentation below is preserved from the original MBASIC 5.21 manual for historical reference.

Syntax

VARPTR(variable)

Description

Returns the memory address of the first byte of data for the specified variable.

In original MBASIC 5.21: - For simple variables: Returns the address where the value is stored - For arrays: Returns the address of the first element - For strings: Returns the address of the string descriptor

The address returned is an integer in the range -32768 to 32767. If negative, add 65536 to get the actual address.

Historical Uses

Passing Arrays to Machine Code

100 DIM A(100)
110 ADDR = VARPTR(A(0))
120 CALL ADDR

Accessing String Data

100 A$ = "HELLO"
110 PTR = VARPTR(A$)

See Also

  • FRE - Arguments to FRE are dummy arguments
  • HELP SET - Display help for a specific setting
  • INKEY$ - Returns either a one-character string containing a character read from the terminal or a null string if no character is pending at the terminal
  • INP - Returns the byte read from port I
  • LIMITS - Display resource usage and interpreter limits
  • NULL - To set the number of nulls to be printed at the end of each line
  • PEEK - Returns the byte (decimal integer in the range 0 to 255) read from memory location I
  • RANDOMIZE - To reseed the random number generator
  • REM - To allow explanatory remarks to be inserted in a program
  • SET (setting) - Configure interpreter settings at runtime
  • SHOW SETTINGS - Display current interpreter settings
  • TRON/TROFF - To trace the execution of program statements
  • USR - Calls the user's assembly language subroutine with the argument X
  • WIDTH - To set the printed line width in number of characters for the terminal or line printer