Im trying to create a function inside a structure, so far i have this code:
typedef struct client_t client_t, *pno;
struct client_t
{
pid_t pid;
char password[TAM_MAX]; // -> 50 chars
pno next;
pno AddClient()
{
/* code */
}
};
int main()
{
client_t client;
//code ..
client.AddClient();
}
Error: client.h:24:2: error: expected ‘:’, ‘,’, ‘;’, ‘}’ or ‘attribute’ before ‘{’ token.
Which is the correct way to do it ?
Answer
It can't be done directly, but you can emulate the same thing using function pointers and explicitly passing the "this" parameter:
typedef struct client_t client_t, *pno;
struct client_t
{
pid_t pid;
char password[TAM_MAX]; // -> 50 chars
pno next;
pno (*AddClient)(client_t *);
};
pno client_t_AddClient(client_t *self) { /* code */ }
int main()
{
client_t client;
client.AddClient = client_t_AddClient; // probably really done in some init fn
//code ..
client.AddClient(&client);
}
It turns out that doing this, however, doesn't really buy you an awful lot. As such, you won't see many C APIs implemented in this style, since you may as well just call your external function and pass the instance.