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Thursday, March 13, 2008

Converting an IP address to an IP Number

IP address (IPv4 / IPv6) is divided into 4 sub-blocks. Each sub-block has a different weight number each powered by 256. IP number is being used in the database because it is efficient to search between a range of number in database.

Beginning IP number and Ending IP Number are calculated based on following formula:
Quote:
IP Number = 16777216*w + 65536*x + 256*y + z (Formula 1)
Quote:whereIP Address = w.x.y.z
Quote:For example, if IP address is "202.186.13.4", then its IP Number "3401190660" is based on the Formula 1.
Quote:IP Address = 202.186.13.4So, w = 202, x = 186, y = 13 and z = 4
Quote:IP Number = 16777216*202 + 65536*186 + 256*13 + 4= 3388997632 + 12189696 + 3328 + 4= 3401190660
To reverse IP number to IP address,Quote:w = int ( IP Number / 16777216 ) % 256x = int ( IP Number / 65536 ) % 256y = int ( IP Number / 256 ) % 256z = int ( IP Number ) % 256where % is the mod operator and int is return the integer part of the division.

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