In that program I want to increment IP address. And I see output like that:
125.23.45.67
126.23.45.67
127.23.45.67
128.23.45.67
129.23.45.67
130.23.45.67
131.23.45.67
132.23.45.67
133.23.45.67
134.23.45.67
But I want to see output like this:
124.23.45.67
124.23.45.68
124.23.45.68
124.23.45.70
124.23.45.71
124.23.45.72
124.23.45.73
124.23.45.74
124.23.45.75
124.23.45.76
Here is program code:
#include <stdlib.h>
#include <stdio.h>
#include <iostream>
using namespace std;
#include "winsock2.h"
#pragma comment(lib,"wsock32.lib")
void main()
{
in_addr adr1;
in_addr adr2;
int i;
adr1.s_addr=inet_addr("124.23.45.67");
adr2.s_addr=inet_addr("as.34.34.56");
if (adr1.s_addr!=INADDR_NONE)
cout << " adr1 correct" << endl;
else
cout << " adr1 incorect " << endl;
if (adr2.s_addr!=INADDR_NONE)
cout << " adr2 correct" << endl;
else
cout << " adr2 incorect" << endl;
cout << inet_ntoa(adr1) << endl;
cout << inet_ntoa(adr2) << endl;
for (i=0;i<10;i++)
{
adr1.s_addr ++;
cout << inet_ntoa(adr1) << endl;
}
}
Big endian and little endian gets another one. Use htonl and ntohl to convert back and forth.
for (i=0;i<10;i++)
{
adr1.s_addr = htonl(ntohl(adr1.s_addr) + 1);
cout << inet_ntoa(adr1) << endl;
}
To increment an IP address you will need to break up the in_addr
object into 4 int
objects (a short int
will also do) and increment the 4th one until it hits 256, and then reset it to 1 and increment the 3rd one, etc. You shouldn't be using ++
on the in_addr
object directly.
EDIT: Okay, so you can properly increment it if you reverse the byte order. I personally wouldn't do it that way. Especially if all you're doing is outputting IP strings and not using them as an in_addr
elsewhere in code.
Instead of using adr1.s_addr
:
adr1.s_addr=inet_addr("124.23.45.67");
adr2.s_addr=inet_addr("as.34.34.56");
Use this:
u_long addr1=inet_addr("124.23.45.67");
And increment addr1
, ie addr1++
the last octet gets incremented.
Or follow this formula:
if IP is A.B.C.D then u_long addr = A + 256*B + 256*256*C + 256*256*256*D
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