A few questions

[KiZ]

Ok, I wasnt sure wether to put this in programming help, but anyway:

--1--
ok, I know what AND, OR, XOR, NOT, NOR, etc do, but what does EQV and IMP do?

--2--
Have you ever had a really strange goings on in Qbasic? Like your simple program not working, you spending an hour trying to find out what the hell is wrong with it, only to eventually give up, Reload Qbasic and try again, only to discover that your program suddenly works perfectly with no "Illegal Function Calls". Happened to me the other day, very strange, I wasnt even messing with POKE or anything...

--3--
My programming computer doesnt like screen 7. The text produced in screen 7 comes up as complete garbage, not even correct characters, the characters it displays are half of two different ones. Ive guessed it was my video card, but anyone any ideas wether its a solvable problem, or am I stuck with it as long as I have that video card?

[Plasma]

3: Not sure why this is happening, but if the font shows up ok in screen 13 then this fix should work for you:

Code:

DEFINT A-Z
SCREEN 13
DEF SEG = &H0
Font1OffL = PEEK(&H43 * 4)
Font1OffH = PEEK(&H43 * 4 + 1)
Font1SegL = PEEK(&H43 * 4 + 2)
Font1SegH = PEEK(&H43 * 4 + 3)
Font2OffL = PEEK(&H1F * 4)
Font2OffH = PEEK(&H1F * 4 + 1)
Font2SegL = PEEK(&H1F * 4 + 2)
Font2SegH = PEEK(&H1F * 4 + 3)
SCREEN 7
POKE &H43 * 4, Font1OffL
POKE &H43 * 4 + 1, Font1OffH
POKE &H43 * 4 + 2, Font1SegL
POKE &H43 * 4 + 3, Font1SegH
POKE &H1F * 4, Font2OffL
POKE &H1F * 4 + 1, Font2OffH
POKE &H1F * 4 + 2, Font2SegL
POKE &H1F * 4 + 3, Font2SegH

[KiZ]

Thanks, will try the fix as soon as I can.

[Agamemnus]

Goto either the FAQ or programming help section for the EQV and IMP answers....

http://faq.qbasicnews.com/?blast=LogicOptimize

[PlayGGY]

There is no point in having EQV.

Instead of:

Code:

IF a = 10 EQV b = 20 THEN CALL doSomething

Do this:

Code:

IF (a = 10) = (b = 20) THEN CALL doSomething

Unless QBs parser is wierd, that is, and thinks you are assigned 'a' and 'b' values.

[Agamemnus]

Or, it transfers this:

Code:

IF (A = 6 AND B = 4) OR (A <> 6 AND B <> 4) THEN...

....to this:

Code:

IF a = 6 EQV b = 4 THEN.....

err EDIT EDIT!

"EQV" is not the same as "=". It acts in the same way when given True=-1, False=0 values, but this is different:

PRINT (7 EQV 8 )
PRINT (7 = 8 )

[PlayGGY]

Or, it transfers this:
"EQV" is not the same as "=". It acts in the same way when given True=-1, False=0 values, but this is different:

PRINT (7 EQV 8 )
PRINT (7 = 8 )

I understand that... look what I had, though:

Code:

IF (a = 10) = (b = 20) THEN CALL doSomething

If both expressions evaluate to the same thing (either true or false), than doSomething would be called.

[na_th_an]

There is no point in having EQV.

Instead of:

Code:

IF a = 10 EQV b = 20 THEN CALL doSomething

Do this:

Code:

IF (a = 10) = (b = 20) THEN CALL doSomething

Unless QBs parser is wierd, that is, and thinks you are assigned 'a' and 'b' values.

Not always. Try this:

Code:

a%=7
b%=8

IF a% EQV b% THEN PRINT a%;" EQV";b%;" !!"
IF a% = b% THEN PRINT a%, " ="; b%; " !!"

[PlayGGY]

na_th_an, with that example, does EQV turn each number into a true/false expression?

If so, the what you would have to do is:

Code:

IF (a = 0) = (b = 0) THEN...

[na_th_an]

Yeah, EQV compares logically, not arithmetically (sp?). That means that it checks for 0 or non-zero. Two values that are non-zero will be EQuiValent. Two values that are zero will be as well.