convert a network address into a dottted string.

Posted on 1998-12-18
Last Modified: 2008-03-03
I want to know how to convert an (int)IP into a standard dotted format string.

I know about inet_ntoa, but I want to do know how to it directly???????

Question by:cosmicmike
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Expert Comment

ID: 1255293
Start by converting the number to a string.  This can be done with the sprintf function.


int main()
int num = 8989;
char the_num[15];
sprintf(the_num, "%i", num);
return 0;

The code above puts the number 8989 into the string the_num.

You could then manipulate this string however you like, including using a function like sprintf again to place '.' where you need.

LVL 32

Expert Comment

ID: 1255294

This won't always work right as it fails to take into account the machine's byte ordering scheme.


I fail to see your reluctance to do it the right way:

#include "stdio.h"
#include "winsock.h"

int main(int argc, char* argv[])
      struct in_addr in;
      in.S_un.S_addr = 0x12345678;

      printf("%s\n", inet_ntoa(in));
      return 0;

Author Comment

ID: 1255295
sorry marcjb your solution is not 100%

ok I have an array of int IP nums and I want to convert them in a for next loop and put the dotted results in a char array !!

LVL 32

Accepted Solution

jhance earned 50 total points
ID: 1255296
OK, how about this?

#include "stdio.h"
#include "winsock.h"

int main(int argc, char* argv[])
      char cIP[16][16];
      int iIP[16] = {0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15};
      int i;

      struct in_addr in;

      for(i=0; i<16; i++){
            in.S_un.S_addr = iIP[i];
            strcpy(cIP[i], inet_ntoa(in));

      for(i=0; i<16; i++){
            printf("0x%x = %s\n", iIP[i], cIP[i]);

      return 0;

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