Convert IP address from hex to dec using strtol()

Question

I put an IP address from frame to struct:

unsigned char destination_address[4];

In my main program I load a struct:

struct ipv4 naglowek_ipv4;
upakuj_ipv4(bufor_eth_ipv4, &naglowek_ipv4);

And try show this in a "human-readable format":

printf("Destination Adress: %ld.%ld.%ld.%ld\n",
    strtol(naglowek_ipv4.destination_address[0],NULL,16),
    strtol(naglowek_ipv4.destination_address[1],NULL,16),
    strtol(naglowek_ipv4.destination_address[2],NULL,16),
    strtol(naglowek_ipv4.destination_address[3]));

This doesn't display the way I think it should. Does anyone have any idea why?

(Anyone more familiar with what "I put an IP address from frame to struct" and other oddities in here mean, please feel free to clarify in an edit, thx) — , Apr 14 '16 at 19:47

score 1 · Accepted Answer · answered Apr 14 '16 at 19:34

1

The destination_address is not a string, it's just array of four bytes. So simplify your call to:

printf("Destination Adress: %d.%d.%d.%d\n",
        naglowek_ipv4.destination_address[0],
        naglowek_ipv4.destination_address[1],
        naglowek_ipv4.destination_address[2],
        naglowek_ipv4.destination_address[3]);

You would notice if you included the declaration of strtol (and also the fact you don't pass enough parameters to the last invocation):

#include <stdlib.h> /* provides strtol() function */

answered Apr 14 '16 at 19:34

Zbynek Vyskovsky - kvr000

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You have right. I too much complicated. Cen you tell me so, how I can change a unsigned short to decimal? The same example but char change to short: unsigned short life_time:8; – DevAxeQuestion Apr 14 '16 at 20:19
@AxelGocan : `printf("%u", (unsigned)life_time)` or to buffer use `char buf[16]; sprintf(buf, "%u", (unsigned)life_time); – Zbynek Vyskovsky - kvr000 Apr 15 '16 at 06:10

Convert IP address from hex to dec using strtol()

1 Answers1