Conditional Logic

Conditional logic commands enable a procedure to test the value of variables or expressions and then branch to appropriate routines.

Command	Description
BeginCase Case statement EndCase	Tests a series of conditions (cases). When any one is met, the statements dependent on that condition are executed. All subsequent condition tests (cases) are skipped.
If conditional expression	Same as single-line If statement, except that the entire statement is evaluated as an expression, returning only one of two values.
If...Then...Else statements	Performs single-line or multiple-line logic. If not single-line, statements for both branches must be delimited with End. Multi-line conditional logic syntax is applicable to all conditional statements (such as Read or Locate statements).
Null statement	A no-op. Used if a statement is called for, but no action is desired (example: If ... Then Null Else ...).
On...GoSub statement	Branches, based on an index, to a series of labels to multiple locations. When the subroutine returns, control returns to the statement following this one.
On...GoTo statement	Branches, based on an index, to a series of labels to multiple locations.
Until/While statement	Establishes exit conditions for a loop created by the Loop ... Repeat or the For...Next statements.