please tell me how to use it in Xcode

[ly886]

i can't install it in my mac computer

liyudeMBP:Desktop liyu$ g++ link.cpp -lpqxx -lpq
liyudeMBP:Desktop liyu$ g++ link.cpp -lpqxx -lpq
liyudeMBP:Desktop liyu$ g++ link.cpp -lpq
Undefined symbols for architecture x86_64:
"pqxx::connection_base::disconnect()", referenced from:
_main in link-f6a0e9.o
"pqxx::connection_base::init()", referenced from:
pqxx::basic_connectionpqxx::connect_direct::basic_connection(char const*) in link-f6a0e9.o
"pqxx::connection_base::close()", referenced from:
pqxx::basic_connectionpqxx::connect_direct::~basic_connection() in link-f6a0e9.o
"pqxx::connection_base::dbname()", referenced from:
_main in link-f6a0e9.o
"pqxx::connection_base::connection_base(pqxx::connectionpolicy&)", referenced from:
pqxx::basic_connectionpqxx::connect_direct::basic_connection(char const*) in link-f6a0e9.o
"pqxx::connectionpolicy::connectionpolicy(std::__1::basic_string<char, std::__1::char_traits, std::__1::allocator > const&)", referenced from:
pqxx::connect_direct::connect_direct(std::__1::basic_string<char, std::__1::char_traits, std::__1::allocator > const&) in link-f6a0e9.o
"pqxx::connectionpolicy::~connectionpolicy()", referenced from:
pqxx::connect_direct::~connect_direct() in link-f6a0e9.o
"pqxx::connection_base::is_open() const", referenced from:
_main in link-f6a0e9.o
"vtable for pqxx::connect_direct", referenced from:
pqxx::connect_direct::connect_direct(std::__1::basic_string<char, std::__1::char_traits, std::__1::allocator > const&) in link-f6a0e9.o
NOTE: a missing vtable usually means the first non-inline virtual member function has no definition.
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
liyudeMBP:Desktop liyu$ g++ link.cpp -lpq -lpqxx

it always have some erro please help me !
thanks

[ly886]

i just want use my xcode to finish a homework how can i link my postgresql with c++ thanks a lot！

[jtv]

The last command failed, and that's normal because you didn't link with libpqxx. But what went wrong with the first two commands? I don't see any errors.