Unresolved external symbol LNK2019 - c++

Question

First of all, I know this question is all over this site but I have looked at almost all of them and can't seem to find out what is wrong. This is in VS 2012. Thanks.
//Socket.h
#pragma once
#include <iostream>
#include <WinSock2.h>
using namespace std;
const int STRLEN = 256;
class Socket
{
protected:
WSADATA wsaData;
SOCKET mySocket;
SOCKET myBackup;
SOCKET acceptSocket;
sockaddr_in myAddress;
public:
Socket();
~Socket();
bool SendData( char* );
bool RecvData( char*, int );
void CloseConnection();
void GetAndSendMessage();
};
class ServerSocket : public Socket
{
public:
void Listen();
void Bind( int port );
void StartHosting( int port );
};
class ClientSocket : public Socket
{
public:
void ConnectToServer( const char *ipAddress, int port );
};
Here's Socket.cpp
//Socket.cpp
#include "stdafx.h"
#include "Socket.h"
Socket::Socket()
{
if( WSAStartup( MAKEWORD(2, 2), &wsaData ) != NO_ERROR )
{
cerr<<"Socket Initialization: Error with WSAStartup\n";
system("pause");
WSACleanup();
exit(10);
}
//Create a socket
mySocket = socket( AF_INET, SOCK_STREAM, IPPROTO_TCP );
if ( mySocket == INVALID_SOCKET )
{
cerr<<"Socket Initialization: Error creating socket"<<endl;
system("pause");
WSACleanup();
exit(11);
}
myBackup = mySocket;
}
Socket::~Socket()
{
WSACleanup();
}
bool Socket::SendData( char *buffer )
{
send( mySocket, buffer, strlen( buffer ), 0 );
return true;
}
bool Socket::RecvData( char *buffer, int size )
{
int i = recv( mySocket, buffer, size, 0 );
buffer[i] = '\0';
return true;
}
void Socket::CloseConnection()
{
//cout<<"CLOSE CONNECTION"<<endl;
closesocket( mySocket );
mySocket = myBackup;
}
void Socket::GetAndSendMessage()
{
char message[STRLEN];
cin.ignore();//without this, it gets the return char from the last cin and ignores the following one!
cout<<"Send > ";
cin.get( message, STRLEN );
SendData( message );
}
void ServerSocket::StartHosting( int port )
{
Bind( port );
Listen();
}
void ServerSocket::Listen()
{
//cout<<"LISTEN FOR CLIENT..."<<endl;
if ( listen ( mySocket, 1 ) == SOCKET_ERROR )
{
cerr<<"ServerSocket: Error listening on socket\n";
system("pause");
WSACleanup();
exit(15);
}
//cout<<"ACCEPT CONNECTION..."<<endl;
acceptSocket = accept( myBackup, NULL, NULL );
while ( acceptSocket == SOCKET_ERROR )
{
acceptSocket = accept( myBackup, NULL, NULL );
}
mySocket = acceptSocket;
}
void ServerSocket::Bind( int port )
{
myAddress.sin_family = AF_INET;
myAddress.sin_addr.s_addr = inet_addr( "0.0.0.0" );
myAddress.sin_port = htons( port );
//cout<<"BIND TO PORT "<<port<<endl;
if ( bind ( mySocket, (SOCKADDR*) &myAddress, sizeof( myAddress) ) == SOCKET_ERROR )
{
cerr<<"ServerSocket: Failed to connect\n";
system("pause");
WSACleanup();
exit(14);
}
}
void ClientSocket::ConnectToServer( const char *ipAddress, int port )
{
myAddress.sin_family = AF_INET;
myAddress.sin_addr.s_addr = inet_addr( ipAddress );
myAddress.sin_port = htons( port );
//cout<<"CONNECTED"<<endl;
if ( connect( mySocket, (SOCKADDR*) &myAddress, sizeof( myAddress ) ) == SOCKET_ERROR )
{
cerr<<"ClientSocket: Failed to connect\n";
system("pause");
WSACleanup();
exit(13);
}
}
And here's stdafx.h
#pragma once
#include "targetver.h"
#define WIN32_LEAN_AND_MEAN // Exclude rarely-used stuff from Windows headers
// Windows Header Files:
#include <windows.h>
// C RunTime Header Files
#include <stdlib.h>
#include <malloc.h>
#include <memory.h>
#include <tchar.h>
// TODO: reference additional headers your program requires here
#include "Socket.h"
And here are my error messages:
1>------ Build started: Project: Client, Configuration: Debug Win32 ------
1> stdafx.cpp
1> Socket.cpp
1> Client.cpp
1> Generating Code...
1>Socket.obj : error LNK2019: unresolved external symbol __imp__accept#12 referenced in function "public: void __thiscall ServerSocket::Listen(void)" (?Listen#ServerSocket##QAEXXZ)
1>Socket.obj : error LNK2019: unresolved external symbol __imp__bind#12 referenced in function "public: void __thiscall ServerSocket::Bind(int)" (?Bind#ServerSocket##QAEXH#Z)
1>Socket.obj : error LNK2019: unresolved external symbol __imp__closesocket#4 referenced in function "public: void __thiscall Socket::CloseConnection(void)" (?CloseConnection#Socket##QAEXXZ)
1>Socket.obj : error LNK2019: unresolved external symbol __imp__connect#12 referenced in function "public: void __thiscall ClientSocket::ConnectToServer(char const *,int)" (?ConnectToServer#ClientSocket##QAEXPBDH#Z)
1>Socket.obj : error LNK2019: unresolved external symbol __imp__htons#4 referenced in function "public: void __thiscall ServerSocket::Bind(int)" (?Bind#ServerSocket##QAEXH#Z)
1>Socket.obj : error LNK2019: unresolved external symbol __imp__inet_addr#4 referenced in function "public: void __thiscall ServerSocket::Bind(int)" (?Bind#ServerSocket##QAEXH#Z)
1>Socket.obj : error LNK2019: unresolved external symbol __imp__listen#8 referenced in function "public: void __thiscall ServerSocket::Listen(void)" (?Listen#ServerSocket##QAEXXZ)
1>Socket.obj : error LNK2019: unresolved external symbol __imp__recv#16 referenced in function "public: bool __thiscall Socket::RecvData(char *,int)" (?RecvData#Socket##QAE_NPADH#Z)
1>Socket.obj : error LNK2019: unresolved external symbol __imp__send#16 referenced in function "public: bool __thiscall Socket::SendData(char *)" (?SendData#Socket##QAE_NPAD#Z)
1>Socket.obj : error LNK2019: unresolved external symbol __imp__socket#12 referenced in function "public: __thiscall Socket::Socket(void)" (??0Socket##QAE#XZ)
1>Socket.obj : error LNK2019: unresolved external symbol __imp__WSAStartup#8 referenced in function "public: __thiscall Socket::Socket(void)" (??0Socket##QAE#XZ)
1>Socket.obj : error LNK2019: unresolved external symbol __imp__WSACleanup#0 referenced in function "public: __thiscall Socket::Socket(void)" (??0Socket##QAE#XZ)
1>C:\Users\ajayp_000\documents\visual studio 2012\Projects\Client\Debug\Client.exe : fatal error LNK1120: 12 unresolved externals
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

Answer 1

The problem is you are not linking against the Ws2_32.lib library. To fix this you can add that to your additional dependencies tab of linker/Input settings for your project. Alternatively (as pointed out by SChepurin in the comments) you can add
#pragma comment(lib, "Ws2_32.lib")
to a source file of your project.

Answer 2

Another way is that click right in your project in visual studio and go to following path and add "Ws2_32.lib" in that.
Linker>Input> Additional Dependencies

Answer 3

Add runtimeobject.lib to the linker Additional Dependencies (in the project property page, under Linker->Input).

Answer 4

Even though this is a linker error. the problem can also occur if you set wrong "Runtime Library" option in
Properties > Configuration properties > C/C++ > Code Generation > Runtime Library
both called binary and calling binary should have the same values
if the property in the calling binary is MTd, then it should be MTd
in called binary.
if the property in the calling binary is MDd, then it should be MDd in called binary.