Ask with "if then"

[gaslouk]

Hello.

I would like to ask about the use of the "if...Then" command when after using,

"if cancelOpp=1 then cancelOpp=0: wait"
if the condition is not true does it continue after the resolvers to read the "wait" command?
If it does not read it when the condition is not false, what other peculiarities does the command have?

The more examples you give me the better it will be for me.

Many thanks to the team in advance for this and other questions I will ask in the future.

[tsh73]

if the condition is not true does it continue after the resolvers to read the "wait" command?

no
Just change "wait" to "print 1" etc and see for yourself

If it does not read it when the condition is not false, what other peculiarities does the command have?

*this* is not "peculiarities"
It really works as it should.

(but IF in LB indeed has a fiew quirks)

Normal operation
'do something if condition is met
if condition then someOperation
'or you can do several operations
if condition then someOperation1:  someOperation2:  someOperation3

'full form: if condition is met, other then it is not
if condition then someOperation else someOtherOperation
'or you can do several operations
if condition then someOperation1:  someOperation2:  someOperation3 else someOtherOperation1: someOtherOperation2

'gotcha:
'now, I myself would NOT put line IF inside line IF for the sake of my sanity

'block form
if condition then
   someOperation
end if

'Gotcha: indents are only for good look, not affect code execution

'nested - someOperation could be another IF

if x>0 then
   if y >1 then
       print "I"
   else
       print "II"
   end if
else
   if y >1 then
       print "VI"
   else
       print "III"
   end if
end if

if condition then   'really any number of operations
   someOperation1
   someOperation2
   someOperation3
end if
'with ELSE part

if condition then
   someOperation
else
   someOtherOperation
end if

if condition then
   someOperation1
   someOperation2
   someOperation3
else
   someOtherOperation1
   someOtherOperation2
end if



Quirks I'm aware of:
non-integer value as condition possibly evaluates wrong (or not as I expect it) (or probably fail with error)
x =1
if x then print "True" else print "false"
x =0
if x then print "True" else print "false"

'now I remember it could fail (runtime error) if x is not integer
'check for yourself. Should it print True or False?
x =0.1
if x then print "True" else print "false"



AND OR does not respect operator precedence

if 1 and 1 or 1 and 0 then print "True" else print "False"
'should work "AND" first, as
if (1 and 1) or (1 and 0) then print "True" else print "False"


[tsh73]

Also
"chaining" conditions - check first one, if not holds then second one, ...
This approach DOES NOT WORK
if cond1 then
   print "action 1"
else if cond2 then
   print "action 2"
else if cond3 then
   print "action 3"
else
   print "action ELSE"
end if


You can nest IF conditions, each with own END IF (as I said, indents are only for look)
But it will require many END IFs
if cond1 then
   print "action 1"
else
   if cond2 then
       print "action 2"
   else
       if cond3 then
           print "action 3"
       else
           print "action ELSE"
       end if
   end if
end if


Or could use SELECT CASE - it's rather powerful in LB (and I think a bit different from QBasic)
select case
case cond1
   print "action 1"
case cond2
   print "action 2"
case cond3
   print "action 3"
case else
   print "action ELSE"
end select


[gaslouk]

Thank you tsh73

Jan 27, 2023 4:16:03 GMT -5 tsh73 said: