错误：“未知类型名称ip4addr_t”

Question

I have a project to generate an IP address using the DHCP protocol. I found code that can help me so I tried to compile it in Ubuntu Linux using gcc . It found some errors; one of them is:

unknown type name ip4addr_t

I don't know if this type is built-in in C, or in some #include I should add? Or should I create a specific type?

This the C code:

typedef ip4adress_t ipaddr_t;
union ip4addr_t
{
  .....
};

Answer 1

Usually, the ip4adress_t is a typedef to unsigned int . However, it is not guaranteed to be the same for all platforms.

Answer 2

If you indeed mean ip4addr_t then you wrote yourself that ip4addr_t is the name of a union.

union ip4addr_t
{
.....
};

So if you get an error that ip4addr_t is unknown type name then it means that some part of your code does not see this union definition.