c - Returning a struct from function -

i'm trying understand how return struct function i'm lost.

here code:

void initialize_server(struct data host_port){          printf(" set ip address (x.x.x.x): ");         fgets(data.host, sizeof(data.host), stdin);         strchomp(data.host);          printf(" set port: ");         fgets(data.port_inc, sizeof(data.port_inc), stdin);         strchomp(data.port_inc);          return data; } 

and heres code .h

struct data{     char host[16];     char port_inc[8]; };  void initialize_server(struct data host_port); 

the function definition

your function definition uses void, defines function returning nothing, therefore return statement useless (will discuss later).

use of structures

also definition seems little broken. have written:

void initialize_server(struct data host_port) { 

then in function write things data.host. i'm assuming have struct definition data somewhere , host_port variable of type struct data.

to create variable of type struct some-struct-name write struct some-struct-name your-variable-name. in code have

struct data {     char host[size];     port_inc[size]; } 

this defines layout of new composite data type. type identified name data. create variables of type declare them follows:

struct data my_new_data_struct;  // data structure on stage of type struct data *my_new_data_struct; // pointer data structure                                   // allocated on heap 

possible solutions

use structures passed value

you write function follows return structure, little inefficient, because returning structure having utilise stack return data , using stack pass in parameter function. called pass-by-value.

struct data initialize_server(struct data host_port)

then replace data. bits host_port.:

void initialize_server(struct data host_port) {         printf(" set ip address (x.x.x.x): ");         fgets(**host_port**.host, sizeof(**host_port**.host), stdin);         strchomp(**host_port**.host);          printf(" set port: ");         fgets(**host_port**.port_inc, sizeof(**host_port**.port_inc), stdin);         strchomp(**host_port**.port_inc);          return **host_port**; } 

use pointers

what might better pass in pointer data structure follows:

void initialize_server(struct data *const host_port) 

this defines function initialize_server returning nothing, won't need return anyway because not host_port pointer. function become:

void initialize_server(struct data *const host_port) {         printf(" set ip address (x.x.x.x): ");         fgets(data.host, sizeof(host_port->host), stdin);         strchomp(host_port->host);          printf(" set port: ");         fgets(host_port->port_inc, sizeof(host_port->port_inc), stdin);         strchomp(host_port->port_inc); } 

but note when call function must pass in pointer! might have like:

void do_something( ) {    struct data my_host_port;    //do stuff    initialize_server( &my_host_port); // note: ampersand!!    // stuff }   

or might malloc() host port follows.

void do_something( ) {    struct data *my_host_port = malloc(sizeof(struct data));    //do stuff    initialize_server(my_host_port); // note: no ampersand my_host_port  pointer!!    // stuff    free(my_host_port); // note: must free() malloc() }