MySQL++ meets Leopard on an Intel Mac

A friend of mine is learning C++ and also wants to learn MySQL. I decided to go ahead and show him how to connect MySQL to a database in C++. Once I started, I realized I've never done this with MySQL, only with PostgreSQL. Oh well, how different could it be???

I decided to install on my Mac Mini which is running MacOS/X 10.5 Leopard. Installing the latest stable version of MySQL from source was cake. I got the sample C program working with no problems and then I looked for how to hookup C++ to MySQL. MySQL itself does not come with a C++ API, only C. The C++ bindings are provided by a project called MySQL++. This is when the problems started.

First off, it gave me some errors about not being able to find some functions. This was the actual error:

./lib/mystring.cpp: In member function ‘int mysqlpp::String::compare(const std::string&) const’:
./lib/mystring.cpp:67: error: no matching function for call to ‘max(unsigned int, size_t)’
./lib/mystring.cpp: In member function ‘int mysqlpp::String::compare(const char*) const’:
./lib/mystring.cpp:81: error: no matching function for call to ‘max(unsigned int, size_t)’
./lib/mystring.cpp: In member function ‘int mysqlpp::String::compare(const std::string&) const’:
./lib/mystring.cpp:67: error: no matching function for call to ‘max(unsigned int, size_t)’
./lib/mystring.cpp: In member function ‘int mysqlpp::String::compare(const char*) const’:
./lib/mystring.cpp:81: error: no matching function for call to ‘max(unsigned int, size_t)’

A little googling around turns up this message on the MySQL++ mailing list. Apparently the way things were coded, this "max" function works perfectly fine on 32 bit processors, but not 64 bit. The fix is to change 1 line of the lib/mystring.h file in the source from "typedef unsigned int size_type;" to "typedef size_t size_type;". It sounds like this fix will be in the next release of MySQL++ and then no one will have to worry about it.

Another note here - the library for MySQL++ isn't libmysql++ or mysql++ as one may expect. It is mysqlpp. Just as well, special characters tend to mess things up sometimes.

The other problem I ran into was this error when trying to compile the sample program from the MySQL++ documentation:

ld: in /usr/local/lib, can't map file, errno=22
collect2: ld returned 1 exit status

This turned out to be one of those silly mistakes that causes a big problem. In specified the linker path, I had put

-L /usr/local/lib

When I changed it to

-L/usr/local/lib

it worked fine. This seems like something the GNU development utilities should be able to be smart enough to handle.