CLEAR¶

Syntax¶

CLEAR [,[<expression1>] [,<expression2>]]

Versions: 8K, Extended, Disk

Purpose¶

To set all numeric variables to zero and all string variables to null; and, optionally, 'to set the end of memory and the amount of stack space.

Remarks¶

CLEAR resets all variables to their initial values (0 for numbers, empty for strings) and optionally configures memory usage.

A CLEAR that succeeds also does these things, as MBASIC 5.21 does:

It removes ON ERROR GOTO, so the next error stops the program. A handler that is running ends, and its RESUME gives "RESUME without error". ERR and ERL keep their values.
It empties the FOR and GOSUB stacks, sends the DATA pointer back to the first item, forgets the DEF FN functions defined so far, and allows OPTION BASE again.
It closes all files.

Difference: DEFINT, DEFSTR and the other type statements are set when the program is read, so CLEAR does not reset them here.

Parameters¶

In MBASIC 5.21 (BASIC-80 release 5.0 and later):

expression1: If specified, sets the highest memory location available for BASIC to use
expression2: Sets the stack space reserved for BASIC (default: 256 bytes or ⅛ of available memory, whichever is smaller)

Memory Management¶

Note about string space: In BASIC-80 release 5.0 and later (including MBASIC 5.21), string space is allocated dynamically from available memory. You'll only get an "Out of string space" error if there's no free memory left. The expression1 parameter does NOT control string space in MBASIC 5.21.

Historical note: In earlier versions of BASIC-80 (before release 5.0), the parameters had different meanings: - expression1 set the amount of string space - expression2 set the end of memory

This behavior changed in release 5.0 to support dynamic string allocation.

Example¶

CLEAR
CLEAR ,32768
CLEAR ,,2000
CLEAR ,32768,2000