[Mysqlcppapi-main] How to convert decimal to double and mediatext to string?

[韩彦军（Hammer） <ya...@do...>]

Hi all, in the example ssqls1.cpp I want to convert the sql_decimal type
to the ordinary c++ double via the following statements:

double d;
d = it->price;

but I got errors when compiling as follows:

lib/null.h: In member function ‘mysqlpp::Null<Type, Behavior>::operator
Type() const [with Type = double, Behavior = mysqlpp::NullIsNull]’:
examples/ssqls1.cpp:72:13: instantiated from here
lib/null.h:55:2: error: ‘mysqlpp::null_type::operator
CannotConvertNullToAnyOtherDataType() const [with
CannotConvertNullToAnyOtherDataType = double]’ is protected
lib/null.h:232:29: error: within this context
make: *** [ssqls1_ssqls1.o] Error 1

Besides, when I convert sql_mediatext type to the c++ string via:

string s;
s = it->description;

I got a similar error:

lib/null.h: In member function ‘mysqlpp::Null<Type, Behavior>::operator
Type() const [with Type = std::basic_string<char>, Behavior =
mysqlpp::NullIsNull]’:
examples/ssqls1.cpp:72:13: instantiated from here
lib/null.h:55:2: error: ‘mysqlpp::null_type::operator
CannotConvertNullToAnyOtherDataType() const [with
CannotConvertNullToAnyOtherDataType = std::basic_string<char>]’ is protected
lib/null.h:232:29: error: within this context
make: *** [ssqls1_ssqls1.o] Error 1

I searched the archive and didn't find any solution. Any suggestion?
Thank you very much!


Regards,
Han