c++ - Error LNK2001 when instantiating a class with parameters within a constructor -

good afternoon,

issue #1

i have mysterious issue, can call class i've defined without issues, if try add parameter constructor, , instantiate class argument, gives 2 lnk2001 errors, 1 constructor , 1 destructor.

error lnk2001: unresolved external symbol "public: __thiscall socket_h::~socket_h(void)" (??1socket_h@@$$fqae@xz) error lnk2001: unresolved external symbol "public: __thiscall socket_h::socket_h(char const *)" (??0socket_h@@$$fqae@pbd@z) 

the code follows:

class header:

class socket_h{ protected:     ;//...  public:      socket_h(const char*);     int receive_data(char* szbuffer);     int send_data(char* szmessage);     ~socket_h(void); }; 

class source:

class socket_h{ protected:          ;//...  public:  socket_h() {     socket_h("192.168.5.100"); }  socket_h(const char* ip_address) {     ;//...; } //... ~socket_h(void) {     closesocket(sclient);      wsacleanup(); } }; 

calling function:

private: system::void read_socket_click(system::object^  sender, system::eventargs^  e) {          socket_h accelerometer("192.168.5.100");  } 

issue #2

i have follow error.

i still looking above issue, in order save time, added method class , changed calling function to:

private: system::void read_socket_click(system::object^  sender, system::eventargs^  e) {           socket_h accelerometer();          accelerometer->setaddress("192.168.5.100", 80); } 

however, error:

error c2227: left of '->setaddress' must point class/struct/union/generic type   1664    1 

i seem have done correctly, , don't understand why may happening. thank you.

you have whole bunch of errors , misconceptions. starting hello world program , reading c++ tutorials you. problems.

issue #1

you forgot declare parameterless constructor in header file:

class socket_h {   ...   socket_h();   ... }; 

your source file looks suspicious too. shouldn't using class socket_h { ... }; in source file anymore. instead define methods , constructors using scope resolution operator:

socket_h::socket_h() {  }  socket_h::socket_h(const char* ip_address) {  }  socket_h::~socket_h(void) {     closesocket(sclient);      wsacleanup(); } 

furthermore, have semantic error constructor chain call:

socket_h::socket_h() {     socket_h("192.168.5.100"); // <--- illegal } 

in c++11 can use delegating constructors follows:

socket_h::socket_h(): socket_h("192.168.5.100") {  } 

however, feature seems not implemented in vc++ 11 yet.

issue #2

change to:

socket_h accelerometer; 

i.e. remove (). otherwise, compiler confuses parameterless function declaration, have name accelerometer , return type socket_h. ambiguity issue known the vexing problem.

change to:

accelerometer.setaddress("192.168.5.100", 80); 

explanation simple: accelerometer not pointer, therefore should not using -> access members , methods. accelerometer instance of socket_h, access members , methods, should use . operator.