Raising a negative number to a power

[paravantis]

It appears that the use of parentheses in the following code gives an invalid delimiter error


Uses "Console"
printl (-2)^2
WaitKey

while the following alternative runs well


Uses "Console"
printl -2^2
WaitKey

On the other hand, the following version gives the wrong answer!


Uses "Console"
printl -(2)^2
WaitKey

So, something is not right with parsing such numerical expressions.

[ErosOlmi]

Problem is in PRINTL
It assumes that the expression to print is a string so parsing consider it as a string and not a number

Try this where I've included your numeric expressions into STR$(...) that assumes to parse a number and convert into a string



Uses "Console"

printl "(-2)^2 =", str$((-2)^2)
printl "-2^2 =", str$(-2^2)
printl "-(2)^2 =", str$(-(2)^2)

WaitKey


thinBasic is a real-time interpreter without any intermediate code.
String parsing try to look ahead to check if next expression can be a numeric expression and not a string, switch into numeric parsing and at the end covert into a string.
But seems there is something to improve here.

Will have a look
Thanks

[ErosOlmi]

Interesting :D

Excel gives 4
Calc gives 4
Google gives -4 but because it transform -(2)^2 into -(2^2) and that gives -4 also in all other programs thinBasic included

[paravantis]

Like you have suggested here and in older posts, I am going to be using


Tstr$(numeric expression)

and plenty of parentheses everywhere, to be on the safe side.