Ambiguous call again

[Anna Smidt]

I am having an "ambiguous call to overloaded function" error again.

This is the function:

int nGetProfWidth (int ncols, unsigned ProfSpec)
{
if ((ProfSpec & PROF_2d) == 0)
return ncols;
return int(sqrt(ncols) ); //HERE THE ERROR IS THROWN
}

When I want to have an integer returned (as in the code above - at least
I think it should return an integer), how should I rewrite this code?

Anna

[David Wilkinson]

Re: Ambiguous call again

Anna Smidt wrote:

I am having an "ambiguous call to overloaded function" error again.
>
This is the function:
>
int nGetProfWidth (int ncols, unsigned ProfSpec)
{
if ((ProfSpec & PROF_2d) == 0)
return ncols;
return int(sqrt(ncols) ); //HERE THE ERROR IS THROWN
}
>
When I want to have an integer returned (as in the code above - at least
I think it should return an integer), how should I rewrite this code?

Anna:

return int(sqrt(double (ncols)));

You do know that most integers do not have an exact integer square root?

--
David Wilkinson
Visual C++ MVP

[Anna Smidt]

Re: Ambiguous call again

You do know that most integers do not have an exact integer square root?

Thanks and...
No, I did not know that. But I was wrong in the first place already
anyway because I was thinking of a VB6 integer which isn't equal to
VC++ integers as far as I know. I'm already tired enough to drop on the
table, so I will look it up tomorrow morning (yes, I have a C++ book :-)

Anna

[Anna Smidt]

Re: Ambiguous call again

Oh, I have a question before I go to bed:

double hypotenuse = sqrt( square(p.y - q.y) + square(p.x - q.x) );

Why is there a space after "sqrt(" and before the last ")"?

[Anna Smidt]

Re: Ambiguous call again

Okay, 1 last question:

MatView Mat::viewAsSqua re ()
{
size_t ncols = size_t(sqrt(thi s->nelems()));
// check that can square properly (assertion is not essential but
protects the user)
ASSERT(ncols * ncols == this->nelems());
return MatView(*this, 0, 0, ncols, ncols, ncols);
}

The compiler tells me

error C2514: 'size_t' : class has no constructors

Why? Sorry for my many questions...
Anna

[David Wilkinson]

Re: Ambiguous call again

Anna Smidt wrote:

>You do know that most integers do not have an exact integer square root?

>
Thanks and...
No, I did not know that. But I was wrong in the first place already
anyway because I was thinking of a VB6 integer which isn't equal to VC++
integers as far as I know. I'm already tired enough to drop on the
table, so I will look it up tomorrow morning (yes, I have a C++ book :-)

Anna:

This has nothing to do with computer languages; it's just math. What is the
integer square root of 20? According to your formula it is 4. This may be the
answer you want; only you know that.

--
David Wilkinson
Visual C++ MVP

[David Wilkinson]

Re: Ambiguous call again

Anna Smidt wrote:

Oh, I have a question before I go to bed:
>
double hypotenuse = sqrt( square(p.y - q.y) + square(p.x - q.x) );
>
Why is there a space after "sqrt(" and before the last ")"?

Anna:

White space (of this kind) is ignored in C and C++ expressions.

--
David Wilkinson
Visual C++ MVP

[David Wilkinson]

Re: Ambiguous call again

Anna Smidt wrote:

Okay, 1 last question:
>
MatView Mat::viewAsSqua re ()
{
size_t ncols = size_t(sqrt(thi s->nelems()));
// check that can square properly (assertion is not essential but
protects the user)
ASSERT(ncols * ncols == this->nelems());
return MatView(*this, 0, 0, ncols, ncols, ncols);
}
>
The compiler tells me
>
error C2514: 'size_t' : class has no constructors

Anna:

I cannot reproduce this on VS2008. What compiler version are you using?

--
David Wilkinson
Visual C++ MVP

[Giovanni Dicanio]

Re: Ambiguous call again


"Anna Smidt" <a.smidt@nospam gmail.comha scritto nel messaggio
news:%23ZPROAkN JHA.4116@TK2MSF TNGP02.phx.gbl. ..

Okay, 1 last question:
>
MatView Mat::viewAsSqua re ()
{
size_t ncols = size_t(sqrt(thi s->nelems()));

Try:

size_t ncols = static_cast< size_t >( sqrt( this->nelems() ) );

Giovanni

[Giovanni Dicanio]

Re: Ambiguous call again


"Anna Smidt" <a.smidt@nospam gmail.comha scritto nel messaggio
news:OVvSx9jNJH A.4428@TK2MSFTN GP04.phx.gbl...

Oh, I have a question before I go to bed:
>
double hypotenuse = sqrt( square(p.y - q.y) + square(p.x - q.x) );
>
Why is there a space after "sqrt(" and before the last ")"?

For readability of code.

Giovanni

[Anna Smidt]

Re: Ambiguous call again

I cannot reproduce this on VS2008. What compiler version are you using?

Where do I find this info?

[Anna Smidt]

Re: Ambiguous call again

Try:

>
size_t ncols = static_cast< size_t >( sqrt( this->nelems() ) );
>
Giovanni

This doesn't help.

[David Wilkinson]

Re: Ambiguous call again

Anna Smidt wrote:

>

>I cannot reproduce this on VS2008. What compiler version are you using?

>
Where do I find this info?

Anna:

I really meant just what version of Visual Studio are you using. If you really
do not know, select "About Microsoft Visual Studio" (or some such) from the Help
menu.

Could you provide a complete example illustrating this problem?

Something like

#include <math.h>

int main()
{
int n = 100;
size_t ncols = size_t(sqrt(dou ble(n)));
ncols; // prevent unused variable warning
return 0;
}

This code compiles fine for me on VS2008. Does it for you?

--
David Wilkinson
Visual C++ MVP

[Bo Persson]

Re: Ambiguous call again

Anna Smidt wrote:

Oh, I have a question before I go to bed:
>
double hypotenuse = sqrt( square(p.y - q.y) + square(p.x - q.x) );
>
Why is there a space after "sqrt(" and before the last ")"?

Because some people believe that it makes to code easier to read.

They are wrong. :-)


And it confuses beginners...


Bo Persson

[Anna Smidt]

Re: Ambiguous call again

Because some people believe that it makes to code easier to read.
They are wrong. :-)
And it confuses beginners...

Agreed :-)