negative to positive

[sequoyan]

Hi,

This is a really easy question I'm sure but I can't figure it out in a simple way.

Let's say I have A + B = C

and A is 100 and B is -200 so C = -100

How can I get C as a positive number?

I need this for a rectangle drawing function I'm writing where the mouse down and mouse up coordinates can be positive or negative.

What I'm really looking for is the difference between A and B as a positive number.

Any help?

Thanks

T

[Dillinger4]

x - y is the same as x + (-y) so in your case wouldnt you get a negative value either way? if this is supposed to be coded why don't you just use C's absolute value?

[si_the_geek]

I'm guessing that as it is rectangles all lines are horizontal or vertical, in which case Something Else's code is a little over the top (but required if lines are at an angle) . In VB you can do this:

C = Abs(A + B)

[Acidic]

If not in VB, then do this:
if C < 0 then
C= 0-C
end if

[CornedBee]

There's an absolute function in nearly every language.
Mathematical notation is
|a|

[CyberCarsten]

You could also multiply by -1

[CornedBee]

C = 0 - C
or
C = -C
is probably faster than
C = C * -1

[CyberCarsten]

And if its in C, you could do
C *=-1;

[CornedBee]

still slower.

[sw_is_great]

C *=-1;

is the same as C = C * (-1)

but C = 0-C is definitely faster(a littttttttttttttttttttttle)