>>-IF--expression--+---+--THEN--instruction--+---+--------------> '-;-' '-;-' >--+--------------------------+-------------------------------->< '-ELSE--instruction--+---+-' '-;-'
IF conditionally processes an instruction or group of instructions depending on the evaluation of the expression. The expression is evaluated and must result in 0 or 1.
The instruction after the THEN is processed only if the result is 1 (true). If you specify an ELSE, the instruction after the ELSE is processed only if the result of the evaluation is 0 (false).
if answer='YES' then say 'OK!'
else say 'Why not?'
Remember that if the ELSE clause is on the same line as the last clause of the THEN part, you need a semicolon before the ELSE.
if answer='YES' then say 'OK!'; else say 'Why not?'
The ELSE binds to the nearest IF at the same level. You can use the NOP instruction to eliminate errors and possible confusion when IF constructs are nested, as in the following example.
If answer = 'YES' Then
If name = 'FRED' Then
say 'OK, Fred.'
Else
nop
Else
say 'Why not?'