Hi all, my question is how can i get a random interger number
i'll explain, on MouseMove Event we got "Sender: TObject; Shift: TShiftState; X, Y: Integer);"
if X = 120..300 i need do something like this
if X=??? then
begin image4.visible:=TRUE;
end
else
begin Image4.Visible:=False;
end;
i have declared a variable like this "num: array[120..300] of integer;"
and try this
if X=num
but i get this message "[Error] Unit10.pas(73): Incompatible types"
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OK ! Lots of confusions here.
Rebelss, you need a little explanation about pascal language :
- What you have declare :
num: array[120..300] of integer;
is not an integer that can have values between 120 and 300 but an array of 181 integer values (300-120+1)
knowing this, the error you received is self explanatory "[Error] Unit10.pas(73): Incompatible types". When you have this error, check what you have in your expression, and you will see that you compare an integer with an array of integer.
- to declare a type that can have only values between 120 and 300
Type
MyRestrictedInt=120..300;
this makes sure that at compile time a value of this type cannot be assigned a value outside the range
(that is not what you need here)
- a random number is different from a variable which value is unknown when executing a portion of code. It is certainly a language mistake from you, but you mislead experts by using appropriate specific terms.
- you can test a number being in a range in one operator IN (which is in fact a test of a value being or not in a set), but only if all values in the set are >=0 and <=255, like :
if Int IN [120..240] // will compile & execute nicely even if Int can have values greater than 255
if Int IN [30..50,80..120, 150] // will test for 2 ranges and one value in one operator
etc...
This is very convenient to write but a bit less efficient to execute than true comparisons as you did.
For the last example, this would translate to :
if ((Int>=30) and (Int<=50)) Or ((Int>=80) and (Int<=20)) Or (Int=150) Then ...
When comparing to ranges that are outside 0..255 you have no choice anyway but to use comparisons
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by: ThievingSixPosted on 2009-11-03 at 16:20:17ID: 25735327
If you need a random integer: Add the Math unit. Use RandomRange(From,To).