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IsDefined

check if an expression has been defined

Syntax 
IsDefined(E)

Description
This function returns true if E is defined, otherwise it returns false. Typically, it is used to check if a name has already been assigned.

To know if a field in a record has been assigned use fields .

Example 
/**/  IsDefined(MyVariable);
false

/**/  MyVariable := 3;
/**/  IsDefined(MyVariable);
true

See Also