string class not standard

**msalters** · Jul 23 '05, 03:53 AM

Re: string class not standard

d...@excite.it wrote:[color=blue]
> In the stroustrup C++ programming language (third edition) i can
> find example like this:
>
> string s1= "Hello";
>
> So I imagine string is a standard class.[/color]

Actually, it's std::string: "class string in namespace std"
[color=blue]
> Furthermore the class in the example is initialized with a
> constructor like this
>
> string::string( );[/color]

[color=blue]
> The strange thing is this:
>
> Under unixWare i've string class declared only with this
> constructor:
>
> string::string( const char* c);
>
> This doesn't seem standard solution! How is it possible?[/color]

Because it's not the standard std::string, but a string in another
namespace? Because it's declared earlier as
string::string( const char* c = 0); and the implementation has a
special case for c==0? Because you missed the other declarations
(e.g, the copy ctor seems to be missing as well)

Regards,
Michiel Salters

**abecedarian@spambob.com** · Jul 23 '05, 03:53 AM

Re: string class not standard

msalters wrote:[color=blue]
> d...@excite.it wrote:[color=green]
> > In the stroustrup C++ programming language (third edition) i can
> > find example like this:
> >
> > string s1= "Hello";
> >
> > So I imagine string is a standard class.[/color]
>
> Actually, it's std::string: "class string in namespace std"[/color]

Standard C++ has no string class.

**Rolf Magnus** · Jul 23 '05, 03:53 AM

Re: string class not standard

djake@excite.it wrote:
[color=blue]
>
> In the stroustrup C++ programming language (third edition) i can
> find example like this:
>
> string s1= "Hello";
>
> So I imagine string is a standard class.[/color]

Yes, it is. Defined in the <string> header in namespace std.
[color=blue]
> Furthermore the class in the example is initialized with a
> constructor like this
>
> string::string( );[/color]

No, it isn't. First, a temporary string is created using a conversion
constructor from const char*, then s1 is copy-constructed from that. The
compiler can omit the temporary and use the conversion constructor to
construct s1 directly.
[color=blue]
> The strange thing is this:
>
> Under unixWare i've string class declared only with this
> constructor:
>
> string::string( const char* c);
>
> This doesn't seem standard solution! How is it possible?[/color]

Either you are using another than the standard string class or your standard
library implementation is broken.
[color=blue]
> Why under unixware the string file contain a similar class with
> invalid constructors?[/color]

Show a minimal compilable program that fails on that compiler, together with
the error message generated by it. This way, we can make sure whether the
error is the compiler's or yours.

**Mike Wahler** · Jul 23 '05, 03:53 AM

Re: string class not standard

<abecedarian@sp ambob.com> wrote in message
news:1115051850 .839815.100250@ f14g2000cwb.goo glegroups.com.. .[color=blue]
> msalters wrote:[color=green]
>> d...@excite.it wrote:[color=darkred]
>> > In the stroustrup C++ programming language (third edition) i can
>> > find example like this:
>> >
>> > string s1= "Hello";
>> >
>> > So I imagine string is a standard class.[/color]
>>
>> Actually, it's std::string: "class string in namespace std"[/color]
>
> Standard C++ has no string class.[/color]

Certainly it does (its standard library does). It's declared
(in namespace 'std') by standard header <string>.

/* completely standard code: */
#include <string>

int main()
{
std::string s("Hello");
return 0;
}

-Mike

**Markus Moll** · Jul 23 '05, 03:53 AM

Re: string class not standard

Hi

abecedarian@spa mbob.com wrote:
[color=blue]
> Standard C++ has no string class.[/color]

Not sure what you mean.

Markus

**abecedarian@spambob.com** · Jul 23 '05, 03:53 AM

Re: string class not standard

Mike Wahler wrote:[color=blue]
> <abecedarian@sp ambob.com> wrote in message[color=green]
> > Standard C++ has no string class.[/color]
>
> Certainly it does (its standard library does). It's declared
> (in namespace 'std') by standard header <string>.[/color]

Look into the header <string>. I bet you don't find a string class
there.

**Howard** · Jul 23 '05, 03:53 AM

Re: string class not standard

<abecedarian@sp ambob.com> wrote in message
news:1115058822 .083288.177890@ g14g2000cwa.goo glegroups.com.. .[color=blue]
> Mike Wahler wrote:[color=green]
>> <abecedarian@sp ambob.com> wrote in message[color=darkred]
>> > Standard C++ has no string class.[/color]
>>
>> Certainly it does (its standard library does). It's declared
>> (in namespace 'std') by standard header <string>.[/color]
>
> Look into the header <string>. I bet you don't find a string class
> there.
>[/color]

The class std::string is most certainly part of the standard C++ language.
It's a template class. It's defined as:

typedef basic_string<ch ar, char_traits<cha r>, allocator<char> > string;

Just because it's a template class, doesn't mean it's not a class!

Check the standard if you don't believe it's part of the language.

-Howard

**Rolf Magnus** · Jul 23 '05, 03:53 AM

Re: string class not standard

abecedarian@spa mbob.com wrote:
[color=blue]
> Mike Wahler wrote:[color=green]
>> <abecedarian@sp ambob.com> wrote in message[color=darkred]
>> > Standard C++ has no string class.[/color]
>>
>> Certainly it does (its standard library does). It's declared
>> (in namespace 'std') by standard header <string>.[/color]
>
> Look into the header <string>. I bet you don't find a string class
> there.[/color]

I looked, and I found one. Well, ok, it isn't in <string> itself in the
standard library implementation I use, but in one that is #included by
<string>, but that doesn't really make a difference.
So what now?

**Abecedarian** · Jul 23 '05, 03:53 AM

Re: string class not standard

Howard wrote:[color=blue]
> <abecedarian@sp ambob.com> wrote in message
> news:1115058822 .083288.177890@ g14g2000cwa.goo glegroups.com.. .[color=green]
> > Mike Wahler wrote:[color=darkred]
> >> <abecedarian@sp ambob.com> wrote in message
> >> > Standard C++ has no string class.
> >>
> >> Certainly it does (its standard library does). It's declared
> >> (in namespace 'std') by standard header <string>.[/color]
> >
> > Look into the header <string>. I bet you don't find a string class
> > there.[/color]
>
> The class std::string is most certainly part of the standard C++[/color]
language.[color=blue]
> It's a template class. It's defined as:
>
> typedef basic_string<ch ar, char_traits<cha r>, allocator<char> >[/color]
string;

BTW, this is a class template.
[color=blue]
> Just because it's a template class, doesn't mean it's not a class![/color]

It's not a class, it's a template with 3 template parameters. If it
were a class usability would be much better. Just look at the compiler
error messages you get using the so called "string class".
[color=blue]
> Check the standard if you don't believe it's part of the language.[/color]

But you just confirmed that there is no string class just a clumsy
basic_string<ch ar, char_traits<cha r>, allocator<char> > class template.

Don't shoot the messenger ... ;-)

**Howard** · Jul 23 '05, 03:53 AM

Re: string class not standard

"Abecedaria n" <abecedarian@sp ambob.com> wrote in message
news:1115066462 .468273.155130@ z14g2000cwz.goo glegroups.com.. .[color=blue]
> Howard wrote:[color=green]
>> <abecedarian@sp ambob.com> wrote in message
>> news:1115058822 .083288.177890@ g14g2000cwa.goo glegroups.com.. .[color=darkred]
>> > Mike Wahler wrote:
>> >> <abecedarian@sp ambob.com> wrote in message
>> >> > Standard C++ has no string class.
>> >>
>> >> Certainly it does (its standard library does). It's declared
>> >> (in namespace 'std') by standard header <string>.
>> >
>> > Look into the header <string>. I bet you don't find a string class
>> > there.[/color]
>>
>> The class std::string is most certainly part of the standard C++[/color]
> language.[color=green]
>> It's a template class. It's defined as:
>>
>> typedef basic_string<ch ar, char_traits<cha r>, allocator<char> >[/color]
> string;
>
> BTW, this is a class template.[/color]

Well, if you want to get technical, the above is just a typedef... an alias
to a template, in this case.
[color=blue]
>[color=green]
>> Just because it's a template class, doesn't mean it's not a class![/color]
>
> It's not a class, it's a template with 3 template parameters. If it
> were a class usability would be much better. Just look at the compiler
> error messages you get using the so called "string class".
>[color=green]
>> Check the standard if you don't believe it's part of the language.[/color]
>
> But you just confirmed that there is no string class just a clumsy
> basic_string<ch ar, char_traits<cha r>, allocator<char> > class template.
>[/color]

What's clumsy about it? Perhaps you're just not comfortable with templates?
[color=blue]
> Don't shoot the messenger ... ;-)[/color]

I always shoot the messenger. Even for good news. I just like doing things
like that. :-O

But, I fail to see your point. You stated that "Standard C++ has no string
class". If all you are saying is that the class std::string is actually a
template, then so what? It's still part of the standard, and you still
create an instance of it just like any other class:

#include <string>
using std::string;

int main()
{
string strA(); // empty string
string strB = "something" ; // copy of "something"
string* pstrA = new string("somethi ng"); // pointer to string containing
"something"
delete pstrA;
}

Your statement that C++ has no such class implies that "string" is not part
of standard C++, and that the OP ought not rely on it. But that's simply
wrong, if that was your intent. If your statement was simply that
std::string is technically a typedef for a template, then you might have
stated that explicitly, instead of simply declaring there was no such class.
(But in that case, why bother making the statement at all?)

-Howard

**Mike Wahler** · Jul 23 '05, 03:54 AM

Re: string class not standard

"Howard" <alicebt@hotmai l.com> wrote in message
news:zsxde.1731 93$cg1.120473@b gtnsc04-news.ops.worldn et.att.net...[color=blue]
>
> #include <string>
> using std::string;
>
> int main()
> {
> string strA(); // empty string[/color]

Not a string at all. A declaration of a function named
'strA()' which returns type 'string'.

Gotcha! :-)

-Mike

**Mike Wahler** · Jul 23 '05, 03:54 AM

Re: string class not standard

"Markus Moll" <moll@rbg.infor matik.tu-darmstadt.de> wrote in message
news:42765d07$0 $7516$9b4e6d93@ newsread2.arcor-online.net...[color=blue]
> Hi
>
> abecedarian@spa mbob.com wrote:
>[color=green]
>> Standard C++ has no string class.[/color]
>
> Not sure what you mean.[/color]

He means that he doesn't consider a class template
specialization to be a type. Why, I don't know.

-Mike

**Rolf Magnus** · Jul 23 '05, 03:54 AM

Re: string class not standard

Abecedarian wrote:
[color=blue][color=green]
>> The class std::string is most certainly part of the standard C++
>> language.
>> It's a template class. It's defined as:
>>
>> typedef basic_string<ch ar, char_traits<cha r>, allocator<char> >[/color]
> string;
>
> BTW, this is a class template.
>[color=green]
>> Just because it's a template class, doesn't mean it's not a class![/color]
>
> It's not a class, it's a template with 3 template parameters.[/color]

std::basic_stri ng is. std::string is not. The former is a class template,
the latter an instance of it, i.e. a class.

**Abecedarian** · Jul 23 '05, 03:54 AM

Re: string class not standard

Rolf Magnus wrote:[color=blue]
> std::basic_stri ng is. std::string is not. The former is a class[/color]
template,[color=blue]
> the latter an instance of it, i.e. a class.[/color]

class template, class template instantiation, class: 3 different
concepts in C++. Mix them and you create confusion.

string class not standard

string class not standard

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment