Hi ! I have a strange problem with a std::ostringstr eam..
code :
#include <sstream>
/*...*/
std::ostringstr eam ss();
ss << "\"\"" << libpath << "\"\" \"\"" << argfilename << "\"\" \"\""
<< outfilename << "\"\""; //line 75
std::string callstring = ss.str(); //line 77
/* ... */
I don't have a undeclared identifier error when declaring std::ostringstr eam
ss();
however, I have thoses stranges errors :
c:\documents and settings\eric\m es documents\progr amming\stdcpp dynamic
code\loadlib.hp p(75) : error C2296: '<<' : illegal, left operand has type
'class std::basic_ostr ingstream<char, struct std::char_trait s<char>,class
std::allocator< char> > (__cdec
l *)(void)'
c:\documents and settings\eric\m es documents\progr amming\stdcpp dynamic
code\loadlib.hp p(75) : error C2297: '<<' : illegal, right operand has type
'char [3]'
c:\documents and settings\eric\m es documents\progr amming\stdcpp dynamic
code\loadlib.hp p(77) : error C2228: left of '.str' must have
class/struct/union type
I use vc++ 6.0
that's a very strange error and I really do not have a clue how to solve
it.. I mean.. ss is not a undeclared identifier.. and it's really defined
as a std::ostringstr eam.. but I have thoses errors...
any help appreciated.. really !!
thanks !
-Eric Boutin 6 3015
Eric Boutin wrote in news:t_******** **************@ weber.videotron .net:
This: std::ostringstr eam ss();
is a function declaration
std::ostringstr eam ss( void );
change it to
std::ostringstr eam ss;
Rob.
-- http://www.victim-prime.dsl.pipex.com/
This is a normal behavior or a behavior from a crappy compiler ?
"Rob Williscroft" <rt*@freenet.RE MOVE.co.uk> a écrit dans le message de
news:Xn******** *************** ***********@195 .129.110.130... Eric Boutin wrote in news:t_******** **************@ weber.videotron .net:
This:
std::ostringstr eam ss();
is a function declaration
std::ostringstr eam ss( void );
change it to
std::ostringstr eam ss;
Rob. -- http://www.victim-prime.dsl.pipex.com/
Eric Boutin wrote in news:eW******** ************@wa gner.videotron. net: This is a normal behavior or a behavior from a crappy compiler ?
Its normal standard conforming behaviour.
[snip]. <<-- hint
Rob.
-- http://www.victim-prime.dsl.pipex.com/
On 03 Dec 2003 11:54:53 GMT, Rob Williscroft
<rt*@freenet.RE MOVE.co.uk> wrote: Eric Boutin wrote in news:eW******** ************@wa gner.videotron. net:
This is a normal behavior or a behavior from a crappy compiler ?
Its normal standard conforming behaviour.
[snip]. <<-- hint
Rob.
I've always been a bit confused by declarations of variables
explicitly calling the default constructor. And now I wonder how would
the compiler not interpret
std::ostringstr eam ss();
as a forward declaration of a function returning an ostringstream.
When exactly is it necessary to add "()" to class instantiation?
Would that only be when instantiating a derived type in the argument
list of a function call like
class bar {};
void foo(bar);
class dbar : bar {};
...........
foo( dbar temp_db() );
?
dan
Dan W. wrote in news:8j******** *************** *********@4ax.c om: On 03 Dec 2003 11:54:53 GMT, Rob Williscroft <rt*@freenet.RE MOVE.co.uk> wrote:
Eric Boutin wrote in news:eW******** ************@wa gner.videotron. net:
I've always been a bit confused by declarations of variables explicitly calling the default constructor. And now I wonder how would the compiler not interpret
std::ostringstr eam ss();
as a forward declaration of a function returning an ostringstream. When exactly is it necessary to add "()" to class instantiation?
Well never (almost). You could write:
std::ostringstr eam ss = std::ostringstr eam();
Unfortunatly it won't work in this case as the streams lack copy-ctor's
but *fortunatly* it unnesassery as the compiler will default construct
ss for you anyway. Would that only be when instantiating a derived type in the argument list of a function call like
The one and only time it's truly usefull to explicitly call a default
constructor is when initialising a POD (int, double, struct without
constructors etc).
struct X
{
int a; /* a is POD no default constuctor */
X() : a() {}
};
Though a( 0 ) would be just as good above. This is truly usfull within
templates.
template < typename T > struct Y
{
T b;
Y() : b() {}
};
Now Y::b is properly initialized even if T is a type (say int)
without a default constructor. Also unless for some reason we
know that T will always be initializable from 0, b( 0 ) won't
work.
class bar {}; void foo(bar); class dbar : bar {}; .......... foo( dbar temp_db() );
Did you mean
foo( bar() );
or maybe
foo( dbar() ); // watch the slicing !!
struct Z { /*whatever*/ };
int foo( Z const &z = Z() )
{
return 0;
}
Not from all of the above the only place I write variable_name() is
in the initialization list of stucts X and Y, otherwise its type().
Rob.
-- http://www.victim-prime.dsl.pipex.com/
Thank you!
I guess I had foggy memories coming up, like in nameless temporary
construction, such as
class foggy_memory {};
....
throw( foggy_memory() );
Such off sightings often throw me off for a sec... ;-) This thread has been closed and replies have been disabled. Please start a new discussion. Similar topics |
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