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Integer IP Addresses

Posted by pfranza

  March 4, 2009

I know that every couple of years I need the snippet of code that helps me convert the integer version of an IP address back and forth to a string. You would think that after all this time I’d be able to write it blind.

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public static String convertIntegerToIp(long ip) {
     StringBuffer buf = new StringBuffer();
      buf.append(((ip >> 24 ) & 0xFF)).append(".")
          .append(((ip >> 16 ) & 0xFF)).append(".")
          .append(((ip >>  8 ) & 0xFF)).append(".")
          .append(( ip        & 0xFF));		
      return buf.toString();
}
 
 public static long convertStringToIntegerIp(String ip) {
     String[] parts = ip.split("\\.");
     return (Long.valueOf(parts[0]) << 24) +
              (Long.valueOf(parts[1]) << 16) +
              (Long.valueOf(parts[2]) << 8) +
              (Long.valueOf(parts[3]));
 }

In C/C++ you can use an unsigned int instead of a long but in java there are no unsigned types and while I know that you can still do this calculation using a signed integer just as well in java, when you print out the address for visual inspection you will get a negative number and it won’t match the c++ printout so I’ve chosen to use a long to store the values.

Enjoy.

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