c++网络编程错误（WSAStartup）

在使用CodeBlocks编译C++程序时， 
编译程序的时候出现如下错误：

undefined reference to `inet_addr@4'
undefined reference to `gethostbyname@4'
undefined reference to `WSAGetLastError@0'
undefined reference to `inet_ntoa@4'
undefined reference to `WSAStartup@8'
undefined reference to `inet_ntoa@4'
undefined reference to `socket@12'
undefined reference to `htons@4'
undefined reference to `bind@12'
undefined reference to `listen@8'
undefined reference to `accept@12'
undefined reference to `recv@16'
undefined reference to `send@16'
undefined reference to `shutdown@8'
undefined reference to `closesocket@4'
undefined reference to `closesocket@4'
undefined reference to `WSACleanup@0'

原因：缺少lib库，编译找不到相应的lib库。

解决办法： 
1. 出现如下的情况 

2. 设置编译器 
  

3.  

4. 导入相应的lib库