non-pointer type warning when initializing vector with NULLs

[Varun Kacholia]

Hi everyone,
I have the following piece of code:
vector<MyClass* > my_vector(10, NULL);

However this throws the following errors:
myfile.cc: warning: converting NULL to non-pointer type
stl_algobase.h: In function `class MyClass ** fill_n<MyClass **, int,
int>(MyClass **, int, const int &)':

While I understand the reasons for fill_n craping out (as it is not
able to get a pointer to the NULL value
passed by me), is there a way to initialize vector with NULLs? Or is it
safe to assume that vectors
will be initialized with NULLs? thanks!

[Frank Schmidt]

Re: non-pointer type warning when initializing vector with NULLs


"Varun Kacholia" <kacholia@gmail .com> schrieb im Newsbeitrag
news:1141261397 .070036.199930@ j33g2000cwa.goo glegroups.com.. .[color=blue]
> Hi everyone,
> I have the following piece of code:
> vector<MyClass* > my_vector(10, NULL);
>
> However this throws the following errors:
> myfile.cc: warning: converting NULL to non-pointer type
> stl_algobase.h: In function `class MyClass ** fill_n<MyClass **, int,
> int>(MyClass **, int, const int &)':
>
> While I understand the reasons for fill_n craping out (as it is not
> able to get a pointer to the NULL value
> passed by me), is there a way to initialize vector with NULLs? Or is it
> safe to assume that vectors
> will be initialized with NULLs? thanks![/color]

I would assume the NULL :S if you are not naive like me you can try a
vector<MyClass* > my_vector(10, (MyClass*)NULL) ;

[BobR]

Re: non-pointer type warning when initializing vector with NULLs


Frank Schmidt wrote in message ...[color=blue]
>
>"Varun Kacholia" <kacholia@gmail .com> schrieb im Newsbeitrag
>news:114126139 7.070036.199930 @j33g2000cwa.go oglegroups.com. ..[color=green]
>> Hi everyone,
>> I have the following piece of code:
>> vector<MyClass* > my_vector(10, NULL);
>>
>> However this throws the following errors:
>> myfile.cc: warning: converting NULL to non-pointer type
>> stl_algobase.h: In function `class MyClass ** fill_n<MyClass **, int,
>> int>(MyClass **, int, const int &)':
>>
>> While I understand the reasons for fill_n craping out (as it is not
>> able to get a pointer to the NULL value
>> passed by me), is there a way to initialize vector with NULLs? Or is it
>> safe to assume that vectors
>> will be initialized with NULLs? thanks![/color]
>
>I would assume the NULL :S if you are not naive like me you can try a
>vector<MyClass *> my_vector(10, (MyClass*)NULL) ;[/color]

What do you think NULL is? Have you looked up it's definition in your
implementation?
[ from my MinGW ]
#ifndef NULL
#ifdef __cplusplus
#define NULL 0
#else
#define NULL ((void*)0)
#endif
#endif

Try:
std::vector<MyC lass*> my_vector( 10, static_cast<MyC lass*>(0) );
// This is a C++ group, why C style cast? <G>

or:
MyClass *tmp(0);
std::vector<MyC lass*> my_vector( 10, tmp );

or simply:
std::vector<MyC lass*> my_vector( 10 );
std::cout<<"Tem p Test my_vector.at(0) = "<<my_vector.at (0)<<std::endl;
// output: Temp Test my_vector.at(0) = 0

I'll let one of the pros 'splain it. <G>
--
Bob R
POVrookie

[Frank Schmidt]

Re: non-pointer type warning when initializing vector with NULLs


"BobR" <RemoveBadBobR@ worldnet.att.ne t> schrieb im Newsbeitrag
news:F9vNf.5342 $J02.457@bgtnsc 04-news.ops.worldn et.att.net...[color=blue]
>
> Frank Schmidt wrote in message ...[color=green]
>>
>>"Varun Kacholia" <kacholia@gmail .com> schrieb im Newsbeitrag
>>news:11412613 97.070036.19993 0@j33g2000cwa.g ooglegroups.com ...[color=darkred]
>>> Hi everyone,
>>> I have the following piece of code:
>>> vector<MyClass* > my_vector(10, NULL);
>>>
>>> However this throws the following errors:
>>> myfile.cc: warning: converting NULL to non-pointer type
>>> stl_algobase.h: In function `class MyClass ** fill_n<MyClass **, int,
>>> int>(MyClass **, int, const int &)':
>>>
>>> While I understand the reasons for fill_n craping out (as it is not
>>> able to get a pointer to the NULL value
>>> passed by me), is there a way to initialize vector with NULLs? Or is it
>>> safe to assume that vectors
>>> will be initialized with NULLs? thanks![/color]
>>
>>I would assume the NULL :S if you are not naive like me you can try a
>>vector<MyClas s*> my_vector(10, (MyClass*)NULL) ;[/color]
>
> What do you think NULL is? Have you looked up it's definition in your
> implementation?[/color]

No, but i saw that NULL does not match the vector type and that therefore
the compiler is choosing a different constructor.

[Ian Collins]

Re: non-pointer type warning when initializing vector with NULLs

Varun Kacholia wrote:[color=blue]
> Hi everyone,
> I have the following piece of code:
> vector<MyClass* > my_vector(10, NULL);
>
> However this throws the following errors:
> myfile.cc: warning: converting NULL to non-pointer type
> stl_algobase.h: In function `class MyClass ** fill_n<MyClass **, int,
> int>(MyClass **, int, const int &)':
>
> While I understand the reasons for fill_n craping out (as it is not
> able to get a pointer to the NULL value
> passed by me), is there a way to initialize vector with NULLs? Or is it
> safe to assume that vectors
> will be initialized with NULLs? thanks!
>[/color]
Why do you want to? I assume you will fill the vector, so why
initialise it? If you do, drop the NULL, the second parameter defaults
to T().

--
Ian Collins.