Re: [sqlite] Yes, NULL is zero, is it?
Thanks everyone for your input.
I am sorry, the error was cause by human error, i.e. my mistake :-P
On 2017-08-31 9:43 PM, Papa wrote:
This is not a SQLite3 problem, it shows to be a MinGW
(mingw32/7.1.0/...) -> Target: 64bit, however, I just wanted to know
if anyone here has experience the same problem.
std::string sql_statement_request;
...
rc = sqlite3_prepare_v2(db,
sql_statement_request.data(),
-1,
&binary_sql_statement,
NULL);
std::cout << binary_sql_statement << std::endl; // ==> 0 (zero)
if (binary_sql_statement != NULL) {
//do something //==> Does not display anything
}
Thanks in advance
--
ArbolOne.ca
Using Fire Fox and Thunderbird.
ArbolOne is composed of students and volunteers dedicated to providing free
services to charitable organizations.
ArbolOne on Java Development in progress [ í ]
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Re: [sqlite] Yes, NULL is zero, is it?
On Fri, Sep 1, 2017 at 9:08 AM, Olivier Mascia wrote: > > The (calling program) bug starts here above. > sql_statement_request.data() is not guaranteed to be zero-terminated (and > generally isn't). > FWIW, it is since std C++11, i.e. .data() and .c_str() are equivalent going forward [1]. It wasn't before, of course, you are right, in pre-C++11 situations. Note that in C++17 and later, std::string implicitly converts [2] to the new std::string_view [3], whose .data() member [4] does behave like the old pre-C++11 .data() of std::string [1]. --DD [1] http://en.cppreference.com/w/cpp/string/basic_string/data [2] http://en.cppreference.com/w/cpp/string/basic_string/operator_basic_string_view [3] http://en.cppreference.com/w/cpp/string/basic_string_view [4] http://en.cppreference.com/w/cpp/string/basic_string_view/data ___ sqlite-users mailing list sqlite-users@mailinglists.sqlite.org http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
Re: [sqlite] Yes, NULL is zero, is it?
> Le 1 sept. 2017 à 03:43, Papa a écrit : > > std::string sql_statement_request; > ... > rc = sqlite3_prepare_v2(db, > sql_statement_request.data(), > -1, The (calling program) bug starts here above. sql_statement_request.data() is not guaranteed to be zero-terminated (and generally isn't). You either have to do: > rc = sqlite3_prepare_v2(db, > sql_statement_request.c_str(), > -1, Or > rc = sqlite3_prepare_v2(db, > sql_statement_request.data(), > (int)sql_statement_request.size(), Whatever else might happen to be wrong with this query, chances are SQLite parses a longer string than you intended and might fail with syntax errors, which would explain you get a null statement pointer. -- Best Regards, Meilleures salutations, Met vriendelijke groeten, Olivier Mascia, http://integral.software ___ sqlite-users mailing list sqlite-users@mailinglists.sqlite.org http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
Re: [sqlite] Yes, NULL is zero, is it?
It would be nice to know what return-code is. One ought to be checking the return code and if-and-only-if the return code is SQLITE_OK was the prepare successful. Without knowing the value of the return-code, examining the statement pointer is only worthwhile after determinine that the prepare was successful ... and looking at the returned statement pointer is not a substitute for checking the return code. if-and-only-if the return code is demonstrably SQLITE_OK AND the statement pointer is NULL/0 AND the statement is not a comment or other no-op, is there anything meaningful to be derived from the fact that the statement pointer is 0/NULL. Only by seeing all of the input SQL statement, the return code, and statement pointer value is it possible to even posit that there is anything wrong at all. --- The fact that there's a Highway to Hell but only a Stairway to Heaven says a lot about anticipated traffic volume. >-Original Message- >From: sqlite-users [mailto:sqlite-users- >boun...@mailinglists.sqlite.org] On Behalf Of Cory Nelson >Sent: Thursday, 31 August, 2017 22:42 >To: SQLite mailing list >Subject: Re: [sqlite] Yes, NULL is zero, is it? > >On Thu, Aug 31, 2017 at 11:01 PM, Simon Slavin >wrote: >> >> >> On 1 Sep 2017, at 4:49am, J Decker wrote: >> >>> That and MinGW defines NULL as 0 if C++ and not void(*) >> >> Oh Gawd, the old C/C++ problem. >> >> Some compilers and IDEs, by default, compile ".c" files as if they >are C++. This leads to all sorts of weird behaviour including both >compiler error messages and programs which compile fine then >misbehave while running. NULL is one of the things C and C++ do >differently. >> >> I’m not saying this is the problem here, merely that it deserves a >mention. > >If you're in any slightly modern compiler, always use nullptr instead >of NULL. > >-- >Cory Nelson >http://int64.org >___ >sqlite-users mailing list >sqlite-users@mailinglists.sqlite.org >http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users ___ sqlite-users mailing list sqlite-users@mailinglists.sqlite.org http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
Re: [sqlite] Yes, NULL is zero, is it?
On Thu, Aug 31, 2017 at 11:01 PM, Simon Slavin wrote: > > > On 1 Sep 2017, at 4:49am, J Decker wrote: > >> That and MinGW defines NULL as 0 if C++ and not void(*) > > Oh Gawd, the old C/C++ problem. > > Some compilers and IDEs, by default, compile ".c" files as if they are C++. > This leads to all sorts of weird behaviour including both compiler error > messages and programs which compile fine then misbehave while running. NULL > is one of the things C and C++ do differently. > > I’m not saying this is the problem here, merely that it deserves a mention. If you're in any slightly modern compiler, always use nullptr instead of NULL. -- Cory Nelson http://int64.org ___ sqlite-users mailing list sqlite-users@mailinglists.sqlite.org http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
Re: [sqlite] Yes, NULL is zero, is it?
On 8/31/2017 11:49 PM, J Decker wrote: That and MinGW defines NULL as 0 if C++ and not void(*) I don't see how this is relevant. The OP isn't doing cout << NULL , they are doing cout << binary_sql_statement , where binary_sql_statement is presumably a sqlite_statement* - definitely a pointer. -- Igor Tandetnik ___ sqlite-users mailing list sqlite-users@mailinglists.sqlite.org http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
Re: [sqlite] Yes, NULL is zero, is it?
On 1 Sep 2017, at 4:49am, J Decker wrote: > That and MinGW defines NULL as 0 if C++ and not void(*) Oh Gawd, the old C/C++ problem. Some compilers and IDEs, by default, compile ".c" files as if they are C++. This leads to all sorts of weird behaviour including both compiler error messages and programs which compile fine then misbehave while running. NULL is one of the things C and C++ do differently. I’m not saying this is the problem here, merely that it deserves a mention. Simon. ___ sqlite-users mailing list sqlite-users@mailinglists.sqlite.org http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
Re: [sqlite] Yes, NULL is zero, is it?
That and MinGW defines NULL as 0 if C++ and not void(*) #ifndef NULL #ifdef __cplusplus #ifndef _WIN64 #define NULL 0 #else #define NULL 0LL #endif /* W64 */ #else #define NULL ((void *)0) #endif #endif On Thu, Aug 31, 2017 at 7:34 PM, Keith Medcalf wrote: > > Ah. Ok. So it prints the pointer value. Thanks. > > > --- > The fact that there's a Highway to Hell but only a Stairway to Heaven says > a lot about anticipated traffic volume. > > > >-Original Message- > >From: sqlite-users [mailto:sqlite-users- > >boun...@mailinglists.sqlite.org] On Behalf Of Igor Tandetnik > >Sent: Thursday, 31 August, 2017 20:32 > >To: sqlite-users@mailinglists.sqlite.org > >Subject: Re: [sqlite] Yes, NULL is zero, is it? > > > >On 8/31/2017 10:20 PM, Keith Medcalf wrote: > >> Why do you think that a pointer to an arbitrary data block can be > >sent to cout? > > > >Because cout provides operator<<(void*) > >-- > >Igor Tandetnik > > > >___ > >sqlite-users mailing list > >sqlite-users@mailinglists.sqlite.org > >http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users > > > > ___ > sqlite-users mailing list > sqlite-users@mailinglists.sqlite.org > http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users > ___ sqlite-users mailing list sqlite-users@mailinglists.sqlite.org http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
Re: [sqlite] Yes, NULL is zero, is it?
Ah. Ok. So it prints the pointer value. Thanks. --- The fact that there's a Highway to Hell but only a Stairway to Heaven says a lot about anticipated traffic volume. >-Original Message- >From: sqlite-users [mailto:sqlite-users- >boun...@mailinglists.sqlite.org] On Behalf Of Igor Tandetnik >Sent: Thursday, 31 August, 2017 20:32 >To: sqlite-users@mailinglists.sqlite.org >Subject: Re: [sqlite] Yes, NULL is zero, is it? > >On 8/31/2017 10:20 PM, Keith Medcalf wrote: >> Why do you think that a pointer to an arbitrary data block can be >sent to cout? > >Because cout provides operator<<(void*) >-- >Igor Tandetnik > >___ >sqlite-users mailing list >sqlite-users@mailinglists.sqlite.org >http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users ___ sqlite-users mailing list sqlite-users@mailinglists.sqlite.org http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
Re: [sqlite] Yes, NULL is zero, is it?
On 8/31/2017 10:20 PM, Keith Medcalf wrote: Why do you think that a pointer to an arbitrary data block can be sent to cout? Because cout provides operator<<(void*) -- Igor Tandetnik ___ sqlite-users mailing list sqlite-users@mailinglists.sqlite.org http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
Re: [sqlite] Yes, NULL is zero, is it?
Works perfectly fine for me with gcc 7.1.0.
Why do you think that a pointer to an arbitrary data block can be sent to cout?
What result are you expecting?
---
The fact that there's a Highway to Hell but only a Stairway to Heaven says a
lot about anticipated traffic volume.
>-Original Message-
>From: sqlite-users [mailto:sqlite-users-
>boun...@mailinglists.sqlite.org] On Behalf Of Papa
>Sent: Thursday, 31 August, 2017 19:43
>To: SQLite Mailing List
>Subject: [sqlite] Yes, NULL is zero, is it?
>
>This is not a SQLite3 problem, it shows to be a MinGW
>(mingw32/7.1.0/...) -> Target: 64bit, however, I just wanted to know
>if
>anyone here has experience the same problem.
>
> std::string sql_statement_request;
> ...
> rc = sqlite3_prepare_v2(db,
> sql_statement_request.data(),
> -1,
> &binary_sql_statement,
> NULL);
> std::cout << binary_sql_statement << std::endl; // ==> 0 (zero)
> if (binary_sql_statement != NULL) {
> //do something //==> Does not display anything
> }
>
>Thanks in advance
>
>--
>ArbolOne.ca
>Using Fire Fox and Thunderbird.
>ArbolOne is composed of students and volunteers dedicated to
>providing free services to charitable organizations.
>ArbolOne on Java Development in progress [ í ]
>
>___
>sqlite-users mailing list
>sqlite-users@mailinglists.sqlite.org
>http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
___
sqlite-users mailing list
sqlite-users@mailinglists.sqlite.org
http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
Re: [sqlite] Yes, NULL is zero, is it?
On 8/31/2017 9:43 PM, Papa wrote: This is not a SQLite3 problem, it shows to be a MinGW (mingw32/7.1.0/...) -> Target: 64bit, however, I just wanted to know if anyone here has experience the same problem. std::string sql_statement_request; ... rc = sqlite3_prepare_v2(db, sql_statement_request.data(), -1, &binary_sql_statement, NULL); std::cout << binary_sql_statement << std::endl; // ==> 0 (zero) Well, apparently, sqlite3_prepare_v2 call failed. Figure out why. I'm not sure I quite grasp the nature of your difficulty. -- Igor Tandetnik ___ sqlite-users mailing list sqlite-users@mailinglists.sqlite.org http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
[sqlite] Yes, NULL is zero, is it?
This is not a SQLite3 problem, it shows to be a MinGW
(mingw32/7.1.0/...) -> Target: 64bit, however, I just wanted to know if
anyone here has experience the same problem.
std::string sql_statement_request;
...
rc = sqlite3_prepare_v2(db,
sql_statement_request.data(),
-1,
&binary_sql_statement,
NULL);
std::cout << binary_sql_statement << std::endl; // ==> 0 (zero)
if (binary_sql_statement != NULL) {
//do something //==> Does not display anything
}
Thanks in advance
--
ArbolOne.ca
Using Fire Fox and Thunderbird.
ArbolOne is composed of students and volunteers dedicated to providing free
services to charitable organizations.
ArbolOne on Java Development in progress [ í ]
___
sqlite-users mailing list
sqlite-users@mailinglists.sqlite.org
http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
