Vector in cpp

[Marcelo]

Hello,

I would like to know how to use the std::vector variable.
I have tried a class something like this, but I get an error and I don't know why...
the error
lib/image.h:13: error: using-declaration for non-member at class scope
lib/image.h:13: error: expected ‘;’ before ‘<’ token

the code
#ifndef IMAGE_H
#define IMAGE_H

#include <stdio.h>

/*Create the class for the images */
class Image {
public:
int w; // The width of the image.
int h; // The height of the image.
int dim; // The dimension of the the image.
//The array RGB type uchar of the image.
std::vector<uns igned char> arr;
};

#endif /* IMAGE_H */

[roberts.noah@gmail.com]

Re: Vector in cpp


Marcelo wrote:[color=blue]
> Hello,
>
> I would like to know how to use the std::vector variable.
> I have tried a class something like this, but I get an error and I don't know why...
> the error
> lib/image.h:13: error: using-declaration for non-member at class scope
> lib/image.h:13: error: expected ';' before '<' token
>
> the code
> #ifndef IMAGE_H
> #define IMAGE_H
>
> #include <stdio.h>[/color]
#include <vector> // I would also change above to cstdio or use c++
streams.[color=blue]
>
> /*Create the class for the images */
> class Image {
> public:
> int w; // The width of the image.
> int h; // The height of the image.
> int dim; // The dimension of the the image.
> //The array RGB type uchar of the image.
> std::vector<uns igned char> arr;
> };
>
> #endif /* IMAGE_H */[/color]

[Marcelo]

Re: Vector in cpp

I suppose that i need this, because then the compilation works just fine.

#include <vector.h>

However, where can I have more documentation about vector type?

thanks a lot

MArcelo

[W Marsh]

Re: Vector in cpp

On Wed, 14 Dec 2005 18:25:40 +0100, Marcelo <mache_1999@yah oo.com>
wrote:
[color=blue]
>Hello,
>
>I would like to know how to use the std::vector variable.
>I have tried a class something like this, but I get an error and I don't know why...
>the error
>lib/image.h:13: error: using-declaration for non-member at class scope
>lib/image.h:13: error: expected ‘;’ before ‘<’ token
>
>the code
>#ifndef IMAGE_H
>#define IMAGE_H
>
>#include <stdio.h>
>
>/*Create the class for the images */
>class Image {
> public:
> int w; // The width of the image.
> int h; // The height of the image.
> int dim; // The dimension of the the image.
> //The array RGB type uchar of the image.
> std::vector<uns igned char> arr;
>};
>
>#endif /* IMAGE_H */[/color]

You forgot #include <vector>.

Also, stdio.h isn't very C++. Are you still using printf? Consider the
alternatives C++ offers you.

[roberts.noah@gmail.com]

Re: Vector in cpp


Marcelo wrote:[color=blue]
> I suppose that i need this, because then the compilation works just fine.
>
> #include <vector.h>[/color]

You are using old, prestandard headers. Leave out the .h

Get "The C++ Standard Library" by Josuttis for documentation.

[osmium]

Re: Vector in cpp

"Marcelo" writes:
[color=blue]
> However, where can I have more documentation about vector type?[/color]

The first two Google hits on <stl reference> are the two main on-line
references, Dinkumware and SGI (nee Sun). Being reference there are pretty
cryptic but there is a lot more on Google you can probably find as easily
for yourself.

[Mike Smith]

Re: Vector in cpp

W Marsh wrote:[color=blue]
>
> Also, stdio.h isn't very C++. Are you still using printf? Consider the
> alternatives C++ offers you.[/color]

C++ itself doesn't really offer a good alternative to printf(), IMO.
Boost does, however.

--
Mike Smith

[Default User]

Re: Vector in cpp

Mike Smith wrote:
[color=blue]
> W Marsh wrote:[color=green]
> >
> > Also, stdio.h isn't very C++. Are you still using printf? Consider
> > the alternatives C++ offers you.[/color]
>
> C++ itself doesn't really offer a good alternative to printf(), IMO.[/color]

I agree, I still use printf when I need a compact way to do formatted
output. I'm not sure what the objection is.
[color=blue]
> Boost does, however.[/color]

Bah, third party, off-topic library :)



Brian

[Mike Smith]

Re: Vector in cpp

Default User wrote:[color=blue]
> Mike Smith wrote:
>
>[color=green]
>>W Marsh wrote:
>>[color=darkred]
>>>Also, stdio.h isn't very C++. Are you still using printf? Consider
>>>the alternatives C++ offers you.[/color]
>>
>>C++ itself doesn't really offer a good alternative to printf(), IMO.[/color]
>
>
> I agree, I still use printf when I need a compact way to do formatted
> output. I'm not sure what the objection is.[/color]

Well, apart from being seen as gauche by the "new C++" crowd, it is kind
of a pain. Suppose you want to generate a string formatted
printf()-style, to do it using otherwise C++-ish style you need to jump
through hoops:

int a = 5;
float b = 3.14;
string c = "blah";

char tmpbuf[HOW_MUCH_TO_ALL OCATE_HERE];
sprintf(tmpbuf, "a = %08d, b = %.2f, c = %s", a, b, c.c_str());
string s(tmpbuf);

It's ironic to have to use character arrays for this sort of thing, when
one of the very reasons that C++ strings were introduced in the first
place was... to eliminate the need to work with character arrays. :-/

--
Mike Smith

[baalbek]

Re: Vector in cpp

Come on, dude!

std::ostringsre am is way better than any printf!

You just need to include the right headers!

What's better:

printf("%s %d", "test", 12);

or this:

std::ostringstr eam o;
cout << o << "test" << 12;

Baalbek


Mike Smith wrote:[color=blue]
> W Marsh wrote:
>[color=green]
>>
>> Also, stdio.h isn't very C++. Are you still using printf? Consider the
>> alternatives C++ offers you.[/color]
>
>
> C++ itself doesn't really offer a good alternative to printf(), IMO.
> Boost does, however.
>
> --
> Mike Smith[/color]

[Neil Cerutti]

Re: Vector in cpp

On 2005-12-16, baalbek <rcs@bgoark.n o> wrote:[color=blue]
> Come on, dude!
>
> std::ostringsre am is way better than any printf!
>
> You just need to include the right headers!
>
> What's better:
>
> printf("%s %d", "test", 12);
>
> or this:
>
> std::ostringstr eam o;
> cout << o << "test" << 12;[/color]

Now write iostream code to do this:

printf("%10.10f %f %.0f" 1000.48702, 23.718, 800.0);

--
Neil Cerutti

[Marcelo Pinto]

Re: Vector in cpp


baalbek escreveu:
[color=blue]
> Come on, dude!
>
> std::ostringsre am is way better than any printf!
>
> You just need to include the right headers!
>
> What's better:
>
> printf("%s %d", "test", 12);
>
> or this:
>
> std::ostringstr eam o;
> cout << o << "test" << 12;[/color]
You forgot the white space after *test*.

The thing I dislike in printf (and family) is:

printf("%d %s", "test ", 12);

The invertion is not clear and the results may be surprising.

HTH,

Marcelo Pinto

[Neil Cerutti]

Re: Vector in cpp

On 2005-12-16, Marcelo Pinto <mpinto70@gmail .com> wrote:[color=blue]
>
> baalbek escreveu:
>[color=green]
>> Come on, dude!
>>
>> std::ostringsre am is way better than any printf!
>>
>> You just need to include the right headers!
>>
>> What's better:
>>
>> printf("%s %d", "test", 12);
>>
>> or this:
>>
>> std::ostringstr eam o;
>> cout << o << "test" << 12;[/color]
> You forgot the white space after *test*.
>
> The thing I dislike in printf (and family) is:
>
> printf("%d %s", "test ", 12);
>
> The invertion is not clear and the results may be surprising.[/color]

Yup. fprintf and friends provide an excellent and convenient
notation, but they are not type safe or extensible. iostreams
provide for type-safe and extensible formatting, at the expense
of convenient notation.

On the other hand, extensibility means that a convenient notation
is possible to implement yourself, as boost did.

--
Neil Cerutti