multiplying with pointers

How can I multiple with pointers initialized?
My compiler keeps telling me its improper use of a pointer but im not trying to use a pointer :-(
I was alway taught to multiple

Code:

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var = constant * constant or var1 = var2 * var3

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or any mix of those, but the compiler thinks that Im using pointers. How can I get around this?

Could you post some of the code that is giving you problems? There isn't any reason for a compiler to interpret that as a pointer statement, so I'm stumped.

Thanks for any assistence you can offer.

Code:

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static int *xpoint, *ypoint, PointY, PointX;
 *ypoint=GetDlgItemInt(hdc, PointY, NULL, TRUE) ;
 *xpoint=GetDlgItemInt(hdc, PointX, NULL, TRUE) ;
 ypoint=ypoint * yspace ;
 xpoint=xpoint * xspace ;

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placing the * operator in variable declarations makes them pointers so xpoint and ypoint are pointers.

yeah , but I dont want them to be treated as pointer in the equation. I want there value to be multiplied. Is there anyway I can do this?

Try this:

Code:

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static int xpoint, ypoint, PointY, PointX;
 ypoint=GetDlgItemInt(hdc, PointY, NULL, TRUE) ;
 xpoint=GetDlgItemInt(hdc, PointX, NULL, TRUE) ;
 ypoint *= yspace ;
 xpoint *= xspace ;

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well, you need to point them at something, at the moment xpoint and ypoint are not initialised(think thats the right word).

Code:

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xpoint = &something;
ypoint = &somethingelse;

*ypoint=GetDlgItemInt(hdc, PointY, NULL, TRUE) ;
*xpoint=GetDlgItemInt(hdc, PointX, NULL, TRUE) ;

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Quote:

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ypoint=ypoint * yspace ;
xpoint=xpoint * xspace ;

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without using the * operator the above code is working on addresses not values. Try this

Code:

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*ypoint = (*ypoint) * yspace ;
*xpoint = (*xpoint) * xspace ;

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just used brackets for clarity.
If yspace and xspace have been declared as pointers also you need to use the * operator with them as well

That worked but another problem...it stops the thread at the first pointer claiming an access violation. Any clue whats wrong?

C_Coder already answered your question. You must make your pointer point to something before you try and use it. (HINT: That's why they're called "pointers", because you make them "point at" something!)

Quzah.

Quote:

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Originally posted by Isometric
Thanks for any assistence you can offer.

Code:

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static int *xpoint, *ypoint, PointY, PointX;
 *ypoint=GetDlgItemInt(hdc, PointY, NULL, TRUE) ;
 *xpoint=GetDlgItemInt(hdc, PointX, NULL, TRUE) ;
 ypoint=ypoint * yspace ;
 xpoint=xpoint * xspace ;

---

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You are not multiplying the data, you are multiplying the adresses. Very dangerous...

It should be *ypoint = *ypoint * yspace
or ypoint[0] = ypoint[0] * yspace

I did that.
That was suggested higher in the thread twice.

All right, gather around... back to compiler and c-programming 101....


A "pointer" is nothing more than a long value. No more. No less.

It just so happens that the compiler expects to treat it with indirection because you have declared your variable as directable with the '*' symbol.

At the very least, if your compiler can't handle pointer multiplication, then coerce each to a long in the multiply.

Otherwise, be very careful of the resultant number because it could easily access a point well beyond that of your physcal and/or virtual RAM. Or it could roll and go negative.... the possibilities are endless!