CareerCup

stringstream strin;
     string ans, valstr;
     int shift = 24;
     for (int i=0; i < 4; i++)
     {
           int val = (num >> shift) &(0xFF); shift -= 8;
           stringstream strin;
           strin << val;
           strin >> valstr;
           ans.append(valstr);
           if (shift>=0) ans.append('.'); 
           
     }

string ipaddress(int num){
        char buffer[37];
        sprintf(buffer, "%d.%d.%d.%d", (num>>24)&0xFF, (num>>16)&0xFF, (num>>8)&0xFF, (num&0xFF));
        return string(buffer);

}

Here is Java code converting using strings

String stringIPAd = String.format("%1$08x", 2314105025L);
		Integer First = Integer.parseInt(stringIPAd.substring(0,2),16);
		Integer Second = Integer.parseInt(stringIPAd.substring(2,4),16);
		Integer Third = Integer.parseInt(stringIPAd.substring(4,6),16);
		Integer Fourth = Integer.parseInt(stringIPAd.substring(6,8),16);
		
		
		System.out.print(First.toString()+".");
		System.out.print(Second.toString()+".");
		System.out.print(Third.toString()+".");
		System.out.println(Fourth.toString());

Here is the approach I took in Java:

package myUtil;

import java.util.Random;

public class IpAddrToString {

  public static String intIpToString (int ipAddr) {

    StringBuilder ipAddrStr = new StringBuilder();
    for (int i=1; i<=3; i++) {
      ipAddrStr.insert(0, "." + String.valueOf(ipAddr & 0xFF));
      ipAddr = ipAddr >> 8;
    }
    ipAddrStr.insert(0, String.valueOf(ipAddr & 0xFF));
    return ipAddrStr.toString();

  }
  
  public static void main(String[] args) {
    
    Random rand = new Random(System.currentTimeMillis());
    int ipAddr = rand.nextInt();
    System.out.println("The string IP for int [" + ipAddr + "] is [" + intIpToString(ipAddr) + "]");

  }
    
}

Note: I elected to use ">>>" (shift in 0's on left side) instead of ">>" (shift in msb on left side) to keep things "clean", though in this case it does not matter (at least functionally, and I assume that ">>>" performs at least as well as ">>", but am not sure of that).

Sample test runs yield:
The string IP for int [262875931] is [15.171.43.27]
The string IP for int [647301379] is [38.149.9.3]
The string IP for int [-1484977025] is [167.125.12.127]

I believe that the negative value in the last example is simply a byproduct of all Java ints being signed.

#include <stdio.h>
#include <string.h>

main()
{
    int ip[]={1,1,1,1,1,1,1,1,0,0,1,0,1,1,1,0};
    int part = 0;
    int i;
    int j;
    for (i = 0; i < 16; i+=4)
    {
        part = 0;
        for(j = i; j < 4; j++)
        {
            part = (part << 1)  | ip[j];
        }
        printf ("%x", part);
    }
    return 0;
}

What is the problem with this code ??.