# Function Reference

IsDeclared

Check if a variable has been declared.

IsDeclared ( expression )

Parameters

expression | string representing name of the variable to be checked.

Return Value

Success: | Returns 1 for Global variable or variable declared outside functions.
Special: | -1 for Local variable.
Failure: | Return 0 when no variable can be found.

Remarks

If there is a need to use IsDeclared() to check that a variable exists, then in most situations Assign() should be used to create/write to the variable and Eval() should be used to read from the variable.

Related

Assign, Eval

Example

If Not IsDeclared ("a") then
MsgBox(0,"", "$a is NOT declared") ; $a has never been assigned
EndIf
$a=1
If IsDeclared ("a") then
MsgBox(0,"", "$a IS declared" ) ; due to previous $a=1 assignment
EndIf