silent silent - 1 year ago 124
C++ Question

winsock compiling error, it cant find the addrinfo structures and some relating functions

I've just started learning winsock through the "Beej's guide to network programming" book. I'm programming under windows and running it through gcc. This is just a start to writing my first server program but it gives me these errors when I try to compile.

/* Server */
#include <iostream>
#include <windows.h>
#include <winsock2.h>
using namespace std;

const int winsockVersion = 2;
#define BACKLOG 10
#define PORT 3000

int main(void){

WSADATA wsadata;
if (WSAStartup(MAKEWORD(winsockVersion,0),&wsadata) == 0){

struct addrinfo hints, *res;

memset(&hints,0,sizeof hints);
hints.ai_family = AF_INET;
hints.ai_socktype = SOCK_STREAM;
hints.ai_flags = AI_PASSIVE;

if ( getaddrinfo(NULL,PORT,&hints,&res) == 0 ){
cout<<"-Call to get addrinfo successful!." << endl;

cout<<"res af_family" << res->ai_family << endl;

//clear stuff
if( WSACleanup() != 0){
cout<<"-WSACleanup unsuccessful" << endl;
cout<<"-WSACleanup successful" << endl;

return 0;

these are the errors I'm receiving

g++ -o server.exe server.cpp -lws2_32
Process started >>>
server.cpp: In function `int main()':
server.cpp:20: error: aggregate `addrinfo hints' has incomplete type and cannot be defined
server.cpp:25: error: `AI_PASSIVE' was not declared in this scope
server.cpp:27: error: `getaddrinfo' was not declared in this scope
server.cpp:31: error: invalid use of undefined type `struct addrinfo'
server.cpp:20: error: forward declaration of `struct addrinfo'
server.cpp:54:2: warning: no newline at end of file
<<< Process finished.

Shouldn't the structures and functions be defined in either windows.h or winsock.h?.


to anyone who stumbles on this, add

#define _WIN32_WINNT 0x501
#include <ws2tcpip.h>

at the top of your source if getaddrinfo says that its undeclared.

Answer Source

You probably want to #include <ws2tcpip.h>. Remember that before Stack Overflow, Google is your friend for this kind of questions : you will get immediate answers from MSDN !

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