global structure pointers

hi!

assume we have a function to print out a header of a specific protocol like ip.
i have my prototype function declared

Code:

---

void print_ip(struct iphdr *ip);

---

in main i initialise a pointer to the header.

Code:

---

struct iphdr *ip;

ip = (struct iphdr *) (DATA_BUFFER + ipheadersize + ethernetheadersize);

---

my problem is that i cant access the pointer in every function itself because its declared in main.

when i write all that as globals, gcc comes up with errors like: initialization makes integer from pointer without a cast.

why is this happening? and why isnt this happening when i initialize the structure pointers in main?

thank you

Post a bit more code, showing how you're trying to do it.

i want to use my code like that:

Code:

---

/*globals*/


#define BUFFER_MAX 2048
char DATA_BUFFER[BUFFER_MAX];


struct headers
{
    int i_size;
    int e_size;
} headersizes;

struct headersizes = {sizeof(iphdr), sizeof(ethhdr)};

struct iphdr *ip;
ip = (struct iphdr *) (DATA_BUFFER + headersizes.e_size + headersizes.i_size);

//protos

void print_ip(struct iphdr *ip);
...
...
int main(int argc, char **argv)
{
    ...
    ...
   
    read(sockfd, DATA_BUFFER, sizeof(DATA_BUFFER)-1);
    //i read everything into the DATA_BUFFER var

    //now i want to call a function to print out the ip header

    print_ip(ip);
    return 0;
}

void print_ip(struct iphdr *ip)
{
    printf("length: %d\n", ip->lenght);
    printf("......the common ip header infos\n");
    ...
    ...
}

---

is there anything wrong with this initialization/assignment of ip?

thanks