EXISTSVARI / EXISTSVARR / EXISTSVARS Functions

EXISTSVARI(string-expression)
EXISTSVARR(string-expression)
EXISTSVARS(string-expression)

Checks whether a variable with the given name currently exists in the BASIC program. Returns TRUE if found, or FALSE otherwise.

• EXISTSVARI → checks for an integer variable.
• EXISTSVARR → checks for a real (floating-point) variable.
• EXISTSVARS → checks for a string variable.

The parameter is a string containing the variable’s name (without value, suffix only implied by function).

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Examples

REM Create a variable
A = 42
 
IF EXISTSVARI("A") THEN
    PRINT "Variable A exists"
ENDIF

REM Example with strings
B$ = "Hello"
 
IF EXISTSVARS("B$") THEN
    PRINT "Variable B$ exists"
ENDIF

REM Useful for checking before SETVAR
varName$ = "SCORE"
IF EXISTSVARI(varName$) = FALSE THEN
    PRINT "Variable not yet created"
ENDIF

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Notes

• Variable name must match exactly, including suffix ($ for strings, # for reals).
• These functions are typically used with SETVARI, SETVARR, and SETVARS to safely determine if a variable can be set or referenced dynamically.
• Existence check does not return the value; it only reports if the variable has been declared or used.
• Using EXISTSVAR* avoids runtime errors when handling dynamically named variables.

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See also: SETVARI · SETVARR · SETVARS