How to convert an IPv4 address into a integer in C

Question

I m looking for a function that will convert a standard IPv4 address into an Integer   Bonus points available for a function that will do the opposite   Solution should be in C

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public bool TryParseIPv4Address string value  out uint result        IPAddress ipAddress       if   IPAddress TryParse value  out ipAddress              ipAddress AddressFamily    System Net Sockets AddressFamily InterNetwork                 result   0          return false             result   BitConverter ToUInt32 ipAddress GetAddressBytes   Reverse   ToArray    0       return true

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I noticed that System Net IPAddress have Address property  System Int64  and constructor  which also accept Int64 data type  So you can use this to convert IP address to from numeric  although not Int32  but Int64  format

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If you were interested in the function not just the answer here is how it is done   int ipToInt int first  int second       int third  int fourth        return Convert ToInt32  first   Math Pow 256  3              second   Math Pow 256  2      third   256    fourth       with first through fourth being the segments of the IPv4 address

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Barry Kelly and  Andrew Hare  actually  I don t think multiplying is the most clear way to do this  alltough correct    An Int32  formatted  IP address  can be seen as the following structure   StructLayout LayoutKind Sequential  Pack   1    struct IPv4Address      public Byte A     public Byte B     public Byte C     public Byte D        to actually cast it from or to an int32 I think you     need to reverse the fields due to little endian   So to convert the ip address 64 233 187 99 you could do    64    0x40   lt  lt  24    0x40000000  233   0xE9   lt  lt  16    0x00E90000  187   0xBB   lt  lt  8     0x0000BB00  99    0x63           0x00000063                       ----------                          0x40E9BB63   so you could add them up using   or you could binairy or them together  Resulting in 0x40E9BB63 which is 1089059683   In my opinion looking in hex it s much easier to see the bytes   So you could write the function as   int ipToInt int first  int second       int third  int fourth        return  first  lt  lt  24     second  lt  lt  16     third  lt  lt  8     fourth

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var ipAddress    10 101 5 56    var longAddress   long Parse string Join     ipAddress Split      Select x   gt  x PadLeft 3   0        Console WriteLine longAddress     Output  10101005056

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Barry Kelly and  Andrew Hare  actually  I don t think multiplying is the most clear way to do this  alltough correct    An Int32  formatted  IP address  can be seen as the following structure   StructLayout LayoutKind Sequential  Pack   1    struct IPv4Address      public Byte A     public Byte B     public Byte C     public Byte D        to actually cast it from or to an int32 I think you     need to reverse the fields due to little endian   So to convert the ip address 64 233 187 99 you could do    64    0x40   lt  lt  24    0x40000000  233   0xE9   lt  lt  16    0x00E90000  187   0xBB   lt  lt  8     0x0000BB00  99    0x63           0x00000063                       ----------                          0x40E9BB63   so you could add them up using   or you could binairy or them together  Resulting in 0x40E9BB63 which is 1089059683   In my opinion looking in hex it s much easier to see the bytes   So you could write the function as   int ipToInt int first  int second       int third  int fourth        return  first  lt  lt  24     second  lt  lt  16     third  lt  lt  8     fourth

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32-bit unsigned integers are IPv4 addresses  Meanwhile  the IPAddress Address property  while deprecated  is an Int64 that returns the unsigned 32-bit value of the IPv4 address  the catch is  it s in network byte order  so you need to swap it around    For example  my local google com is at 64 233 187 99  That s equivalent to   64 2 24   233 2 16   187 2 8   99   1089059683   And indeed  http   1089059683  works as expected  at least in Windows  tested with IE  Firefox and Chrome  doesn t work on iPhone though    Here s a test program to show both conversions  including the network host byte swapping   using System  using System Net   class App       static long ToInt string addr                   careful of sign extension  convert to uint first             unsigned NetworkToHostOrder ought to be provided          return  long   uint  IPAddress NetworkToHostOrder                int  IPAddress Parse addr  Address              static string ToAddr long address                return IPAddress Parse address ToString    ToString               This also works             return new IPAddress  uint  IPAddress HostToNetworkOrder                 int  address   ToString               static void Main                 Console WriteLine ToInt  64 233 187 99             Console WriteLine ToAddr 1089059683

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Assembled several of the above answers into an extension method that handles the Endianness of the machine and handles IPv4 addresses that were mapped to IPv6   public static class IPAddressExtensions            lt summary gt          Converts IPv4 and IPv4 mapped to IPv6 addresses to an unsigned integer           lt  summary gt           lt param name  address  gt The address to conver lt  param gt           lt returns gt An unsigned integer that represents an IPv4 address  lt  returns gt      public static uint ToUint this IPAddress address                if  address AddressFamily    AddressFamily InterNetwork    address IsIPv4MappedToIPv6                        var bytes   address GetAddressBytes                if  BitConverter IsLittleEndian                  Array Reverse bytes                return BitConverter ToUInt32 bytes  0                     throw new ArgumentOutOfRangeException  address    Address must be IPv4 or IPv4 mapped to IPv6              Unit tests    TestClass  public class IPAddressExtensionsTests        TestMethod      public void SimpleIp1                 var ip   IPAddress Parse  0 0 0 15            uint expected   GetExpected 0  0  0  15           Assert AreEqual expected  ip ToUint                TestMethod      public void SimpleIp2                 var ip   IPAddress Parse  0 0 1 15            uint expected   GetExpected 0  0  1  15           Assert AreEqual expected  ip ToUint                TestMethod      public void SimpleIpSix1                 var ip   IPAddress Parse  0 0 0 15   MapToIPv6            uint expected   GetExpected 0  0  0  15           Assert AreEqual expected  ip ToUint                TestMethod      public void SimpleIpSix2                 var ip   IPAddress Parse  0 0 1 15   MapToIPv6            uint expected   GetExpected 0  0  1  15           Assert AreEqual expected  ip ToUint                TestMethod      public void HighBits                 var ip   IPAddress Parse  200 12 1 15   MapToIPv6            uint expected   GetExpected 200  12  1  15           Assert AreEqual expected  ip ToUint               uint GetExpected uint a  uint b  uint c  uint d                return              a   256u   256u   256u                 b   256u   256u                 c   256u                 d

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public static Int32 getLongIPAddress string ipAddress                return IPAddress NetworkToHostOrder BitConverter ToInt32 IPAddress Parse ipAddress  GetAddressBytes    0            The above example would be the way I go    Only thing you might have to do is convert to a UInt32 for display purposes  or string purposes including using it as a long address in string form   Which is what is needed when using the IPAddress Parse String  function   Sigh

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32-bit unsigned integers are IPv4 addresses  Meanwhile  the IPAddress Address property  while deprecated  is an Int64 that returns the unsigned 32-bit value of the IPv4 address  the catch is  it s in network byte order  so you need to swap it around    For example  my local google com is at 64 233 187 99  That s equivalent to   64 2 24   233 2 16   187 2 8   99   1089059683   And indeed  http   1089059683  works as expected  at least in Windows  tested with IE  Firefox and Chrome  doesn t work on iPhone though    Here s a test program to show both conversions  including the network host byte swapping   using System  using System Net   class App       static long ToInt string addr                   careful of sign extension  convert to uint first             unsigned NetworkToHostOrder ought to be provided          return  long   uint  IPAddress NetworkToHostOrder                int  IPAddress Parse addr  Address              static string ToAddr long address                return IPAddress Parse address ToString    ToString               This also works             return new IPAddress  uint  IPAddress HostToNetworkOrder                 int  address   ToString               static void Main                 Console WriteLine ToInt  64 233 187 99             Console WriteLine ToAddr 1089059683

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Davy Ladman your solution with shift are corrent but only for ip starting with number less or equal 99  infact first octect must be cast up to long   Anyway convert back with long type is quite difficult because store 64 bit  not 32 for Ip  and fill 4 bytes with zeroes  static uint ToInt string addr       return BitConverter ToUInt32 IPAddress Parse addr  GetAddressBytes    0      static string ToAddr uint address        return new IPAddress address  ToString        Enjoy   Massimo

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I have encountered some problems with the described solutions  when facing IP Adresses with a very  large value  The result would be  that the byte 0    16777216 thingy would overflow and become a negative int value  what fixed it for me  is the a simple type casting operation  public static long ConvertIPToLong string ipAddress        System Net IPAddress ip       if  System Net IPAddress TryParse ipAddress  out ip                 byte   bytes   ip GetAddressBytes             return             16777216L   bytes 0                65536   bytes 1                256   bytes 2                bytes 3                          else         return 0

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As noone posted the code that uses BitConverter and actually checks the endianness  here goes   byte   ip   address Split      Select s   gt  Byte Parse s   ToArray    if  BitConverter IsLittleEndian      Array Reverse ip     int num   BitConverter ToInt32 ip  0     and back   byte   ip   BitConverter GetBytes num   if  BitConverter IsLittleEndian      Array Reverse ip     string address   String Join      ip Select n   gt  n ToString

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With the UInt32 in the proper little-endian format  here are two simple conversion functions   public uint GetIpAsUInt32 string ipString        IPAddress address   IPAddress Parse ipString        byte   ipBytes   address GetAddressBytes         Array Reverse ipBytes        return BitConverter ToUInt32 ipBytes  0      public string GetIpAsString uint ipVal        byte   ipBytes   BitConverter GetBytes ipVal        Array Reverse ipBytes        return new IPAddress ipBytes  ToString

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I have encountered some problems with the described solutions  when facing IP Adresses with a very  large value  The result would be  that the byte 0    16777216 thingy would overflow and become a negative int value  what fixed it for me  is the a simple type casting operation  public static long ConvertIPToLong string ipAddress        System Net IPAddress ip       if  System Net IPAddress TryParse ipAddress  out ip                 byte   bytes   ip GetAddressBytes             return             16777216L   bytes 0                65536   bytes 1                256   bytes 2                bytes 3                          else         return 0

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here s a solution that I worked out today  should ve googled first         private static string IpToDecimal2 string ipAddress                   need a shift counter         int shift   3              loop through the octets and compute the decimal version         var octets   ipAddress Split      Select p   gt  long Parse p            return octets Aggregate 0L   total  octet    gt   total    octet  lt  lt   shift--   8     ToString            i m using LINQ  lambda and some of the extensions on generics  so while it produces the same result it uses some of the new language features and you can do it in three lines of code   i have the explanation on my blog if you re interested   cheers  -jc

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var address   IPAddress Parse  10 0 11 174   GetAddressBytes    long m Address     address 3   lt  lt  24   address 2   lt  lt  16   address 1   lt  lt  8   address 0    amp  0x0FFFFFFFF

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public bool TryParseIPv4Address string value  out uint result        IPAddress ipAddress       if   IPAddress TryParse value  out ipAddress              ipAddress AddressFamily    System Net Sockets AddressFamily InterNetwork                 result   0          return false             result   BitConverter ToUInt32 ipAddress GetAddressBytes   Reverse   ToArray    0       return true

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Try this ones   private int IpToInt32 string ipAddress       return BitConverter ToInt32 IPAddress Parse ipAddress  GetAddressBytes   Reverse   ToArray    0      private string Int32ToIp int ipAddress       return new IPAddress BitConverter GetBytes ipAddress  Reverse   ToArray    ToString

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If you were interested in the function not just the answer here is how it is done   int ipToInt int first  int second       int third  int fourth        return Convert ToInt32  first   Math Pow 256  3              second   Math Pow 256  2      third   256    fourth       with first through fourth being the segments of the IPv4 address

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The reverse of Davy Landman s function  string IntToIp int d      int v1   d  amp  0xff    int v2    d  gt  gt  8   amp  0xff    int v3    d  gt  gt  16   amp  0xff    int v4    d  gt  gt  24     return v4         v3         v2         v1

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I think this is wrong   65536      0 0 255 255  Should be   65535      0 0 255 255  or  65536      0 1 0 0

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here s a solution that I worked out today  should ve googled first         private static string IpToDecimal2 string ipAddress                   need a shift counter         int shift   3              loop through the octets and compute the decimal version         var octets   ipAddress Split      Select p   gt  long Parse p            return octets Aggregate 0L   total  octet    gt   total    octet  lt  lt   shift--   8     ToString            i m using LINQ  lambda and some of the extensions on generics  so while it produces the same result it uses some of the new language features and you can do it in three lines of code   i have the explanation on my blog if you re interested   cheers  -jc

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var address   IPAddress Parse  10 0 11 174   GetAddressBytes    long m Address     address 3   lt  lt  24   address 2   lt  lt  16   address 1   lt  lt  8   address 0    amp  0x0FFFFFFFF

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Barry Kelly and  Andrew Hare  actually  I don t think multiplying is the most clear way to do this  alltough correct    An Int32  formatted  IP address  can be seen as the following structure   StructLayout LayoutKind Sequential  Pack   1    struct IPv4Address      public Byte A     public Byte B     public Byte C     public Byte D        to actually cast it from or to an int32 I think you     need to reverse the fields due to little endian   So to convert the ip address 64 233 187 99 you could do    64    0x40   lt  lt  24    0x40000000  233   0xE9   lt  lt  16    0x00E90000  187   0xBB   lt  lt  8     0x0000BB00  99    0x63           0x00000063                       ----------                          0x40E9BB63   so you could add them up using   or you could binairy or them together  Resulting in 0x40E9BB63 which is 1089059683   In my opinion looking in hex it s much easier to see the bytes   So you could write the function as   int ipToInt int first  int second       int third  int fourth        return  first  lt  lt  24     second  lt  lt  16     third  lt  lt  8     fourth

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Try this ones   private int IpToInt32 string ipAddress       return BitConverter ToInt32 IPAddress Parse ipAddress  GetAddressBytes   Reverse   ToArray    0      private string Int32ToIp int ipAddress       return new IPAddress BitConverter GetBytes ipAddress  Reverse   ToArray    ToString

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My question was closed  I have no idea why   The accepted answer here is not the same as what I need    This gives me the correct integer value for an IP    public double IPAddressToNumber string IPaddress        int i      string    arrDec      double num   0      if  IPaddress                      return 0            else               arrDec   IPaddress Split               for i   arrDec Length - 1  i  gt   0   i   i -1                                num      int Parse arrDec i   256    Math Pow 256   3 - i                            return num

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My question was closed  I have no idea why   The accepted answer here is not the same as what I need    This gives me the correct integer value for an IP    public double IPAddressToNumber string IPaddress        int i      string    arrDec      double num   0      if  IPaddress                      return 0            else               arrDec   IPaddress Split               for i   arrDec Length - 1  i  gt   0   i   i -1                                num      int Parse arrDec i   256    Math Pow 256   3 - i                            return num

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Multiply all the parts of the IP number by powers of 256  256x256x256  256x256  256 and 1  For example  IPv4 address   127 0 0 1 32 bit number     127x256 3     0x256 2     0x256 1    1   2130706433

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As noone posted the code that uses BitConverter and actually checks the endianness  here goes   byte   ip   address Split      Select s   gt  Byte Parse s   ToArray    if  BitConverter IsLittleEndian      Array Reverse ip     int num   BitConverter ToInt32 ip  0     and back   byte   ip   BitConverter GetBytes num   if  BitConverter IsLittleEndian      Array Reverse ip     string address   String Join      ip Select n   gt  n ToString

User · Answer

I noticed that System Net IPAddress have Address property  System Int64  and constructor  which also accept Int64 data type  So you can use this to convert IP address to from numeric  although not Int32  but Int64  format

User · Answer

Take a look at some of the crazy parsing examples in  Net s IPAddress Parse   MSDN    65536      0 0 255 255  20 2      20 0 0 2  20 65535      20 0 255 255  128 1 2      128 1 0 2

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var ipAddress    10 101 5 56    var longAddress   long Parse string Join     ipAddress Split      Select x   gt  x PadLeft 3   0        Console WriteLine longAddress     Output  10101005056

User · Answer

32-bit unsigned integers are IPv4 addresses  Meanwhile  the IPAddress Address property  while deprecated  is an Int64 that returns the unsigned 32-bit value of the IPv4 address  the catch is  it s in network byte order  so you need to swap it around    For example  my local google com is at 64 233 187 99  That s equivalent to   64 2 24   233 2 16   187 2 8   99   1089059683   And indeed  http   1089059683  works as expected  at least in Windows  tested with IE  Firefox and Chrome  doesn t work on iPhone though    Here s a test program to show both conversions  including the network host byte swapping   using System  using System Net   class App       static long ToInt string addr                   careful of sign extension  convert to uint first             unsigned NetworkToHostOrder ought to be provided          return  long   uint  IPAddress NetworkToHostOrder                int  IPAddress Parse addr  Address              static string ToAddr long address                return IPAddress Parse address ToString    ToString               This also works             return new IPAddress  uint  IPAddress HostToNetworkOrder                 int  address   ToString               static void Main                 Console WriteLine ToInt  64 233 187 99             Console WriteLine ToAddr 1089059683

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Assembled several of the above answers into an extension method that handles the Endianness of the machine and handles IPv4 addresses that were mapped to IPv6   public static class IPAddressExtensions            lt summary gt          Converts IPv4 and IPv4 mapped to IPv6 addresses to an unsigned integer           lt  summary gt           lt param name  address  gt The address to conver lt  param gt           lt returns gt An unsigned integer that represents an IPv4 address  lt  returns gt      public static uint ToUint this IPAddress address                if  address AddressFamily    AddressFamily InterNetwork    address IsIPv4MappedToIPv6                        var bytes   address GetAddressBytes                if  BitConverter IsLittleEndian                  Array Reverse bytes                return BitConverter ToUInt32 bytes  0                     throw new ArgumentOutOfRangeException  address    Address must be IPv4 or IPv4 mapped to IPv6              Unit tests    TestClass  public class IPAddressExtensionsTests        TestMethod      public void SimpleIp1                 var ip   IPAddress Parse  0 0 0 15            uint expected   GetExpected 0  0  0  15           Assert AreEqual expected  ip ToUint                TestMethod      public void SimpleIp2                 var ip   IPAddress Parse  0 0 1 15            uint expected   GetExpected 0  0  1  15           Assert AreEqual expected  ip ToUint                TestMethod      public void SimpleIpSix1                 var ip   IPAddress Parse  0 0 0 15   MapToIPv6            uint expected   GetExpected 0  0  0  15           Assert AreEqual expected  ip ToUint                TestMethod      public void SimpleIpSix2                 var ip   IPAddress Parse  0 0 1 15   MapToIPv6            uint expected   GetExpected 0  0  1  15           Assert AreEqual expected  ip ToUint                TestMethod      public void HighBits                 var ip   IPAddress Parse  200 12 1 15   MapToIPv6            uint expected   GetExpected 200  12  1  15           Assert AreEqual expected  ip ToUint               uint GetExpected uint a  uint b  uint c  uint d                return              a   256u   256u   256u                 b   256u   256u                 c   256u                 d

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My question was closed  I have no idea why   The accepted answer here is not the same as what I need    This gives me the correct integer value for an IP    public double IPAddressToNumber string IPaddress        int i      string    arrDec      double num   0      if  IPaddress                      return 0            else               arrDec   IPaddress Split               for i   arrDec Length - 1  i  gt   0   i   i -1                                num      int Parse arrDec i   256    Math Pow 256   3 - i                            return num

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If you were interested in the function not just the answer here is how it is done   int ipToInt int first  int second       int third  int fourth        return Convert ToInt32  first   Math Pow 256  3              second   Math Pow 256  2      third   256    fourth       with first through fourth being the segments of the IPv4 address

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Barry Kelly and  Andrew Hare  actually  I don t think multiplying is the most clear way to do this  alltough correct    An Int32  formatted  IP address  can be seen as the following structure   StructLayout LayoutKind Sequential  Pack   1    struct IPv4Address      public Byte A     public Byte B     public Byte C     public Byte D        to actually cast it from or to an int32 I think you     need to reverse the fields due to little endian   So to convert the ip address 64 233 187 99 you could do    64    0x40   lt  lt  24    0x40000000  233   0xE9   lt  lt  16    0x00E90000  187   0xBB   lt  lt  8     0x0000BB00  99    0x63           0x00000063                       ----------                          0x40E9BB63   so you could add them up using   or you could binairy or them together  Resulting in 0x40E9BB63 which is 1089059683   In my opinion looking in hex it s much easier to see the bytes   So you could write the function as   int ipToInt int first  int second       int third  int fourth        return  first  lt  lt  24     second  lt  lt  16     third  lt  lt  8     fourth

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Take a look at some of the crazy parsing examples in  Net s IPAddress Parse   MSDN    65536      0 0 255 255  20 2      20 0 0 2  20 65535      20 0 255 255  128 1 2      128 1 0 2

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If you were interested in the function not just the answer here is how it is done   int ipToInt int first  int second       int third  int fourth        return Convert ToInt32  first   Math Pow 256  3              second   Math Pow 256  2      third   256    fourth       with first through fourth being the segments of the IPv4 address

User · Answer

Take a look at some of the crazy parsing examples in  Net s IPAddress Parse   MSDN    65536      0 0 255 255  20 2      20 0 0 2  20 65535      20 0 255 255  128 1 2      128 1 0 2

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Assuming you have an IP Address in string format  eg  254 254 254 254   string   vals   inVal Split       uint output   0  for  byte i   0  i  lt  vals Length  i    output     uint  byte Parse vals i    lt  lt  8    vals GetUpperBound 0  - i

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I think this is wrong   65536      0 0 255 255  Should be   65535      0 0 255 255  or  65536      0 1 0 0

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Here s a pair of methods to convert from IPv4 to a correct integer and back   public static uint ConvertFromIpAddressToInteger string ipAddress        var address   IPAddress Parse ipAddress       byte   bytes   address GetAddressBytes            flip big-endian network order  to little-endian     if  BitConverter IsLittleEndian                Array Reverse bytes              return BitConverter ToUInt32 bytes  0      public static string ConvertFromIntegerToIpAddress uint ipAddress        byte   bytes   BitConverter GetBytes ipAddress           flip little-endian to big-endian network order      if  BitConverter IsLittleEndian                Array Reverse bytes              return new IPAddress bytes  ToString        Example  ConvertFromIpAddressToInteger  255 255 255 254       4294967294 ConvertFromIntegerToIpAddress 4294967294      255 255 255 254   Explanation  IP addresses are in network order  big-endian   while ints are little-endian on Windows  so to get a correct value  you must reverse the bytes before converting on a little-endian system   Also  even for IPv4  an int can t hold addresses bigger than 127 255 255 255  e g  the broadcast address  255 255 255 255   so use a uint

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With the UInt32 in the proper little-endian format  here are two simple conversion functions   public uint GetIpAsUInt32 string ipString        IPAddress address   IPAddress Parse ipString        byte   ipBytes   address GetAddressBytes         Array Reverse ipBytes        return BitConverter ToUInt32 ipBytes  0      public string GetIpAsString uint ipVal        byte   ipBytes   BitConverter GetBytes ipVal        Array Reverse ipBytes        return new IPAddress ipBytes  ToString

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My question was closed  I have no idea why   The accepted answer here is not the same as what I need    This gives me the correct integer value for an IP    public double IPAddressToNumber string IPaddress        int i      string    arrDec      double num   0      if  IPaddress                      return 0            else               arrDec   IPaddress Split               for i   arrDec Length - 1  i  gt   0   i   i -1                                num      int Parse arrDec i   256    Math Pow 256   3 - i                            return num

User · Answer

32-bit unsigned integers are IPv4 addresses  Meanwhile  the IPAddress Address property  while deprecated  is an Int64 that returns the unsigned 32-bit value of the IPv4 address  the catch is  it s in network byte order  so you need to swap it around    For example  my local google com is at 64 233 187 99  That s equivalent to   64 2 24   233 2 16   187 2 8   99   1089059683   And indeed  http   1089059683  works as expected  at least in Windows  tested with IE  Firefox and Chrome  doesn t work on iPhone though    Here s a test program to show both conversions  including the network host byte swapping   using System  using System Net   class App       static long ToInt string addr                   careful of sign extension  convert to uint first             unsigned NetworkToHostOrder ought to be provided          return  long   uint  IPAddress NetworkToHostOrder                int  IPAddress Parse addr  Address              static string ToAddr long address                return IPAddress Parse address ToString    ToString               This also works             return new IPAddress  uint  IPAddress HostToNetworkOrder                 int  address   ToString               static void Main                 Console WriteLine ToInt  64 233 187 99             Console WriteLine ToAddr 1089059683

User · Answer

Multiply all the parts of the IP number by powers of 256  256x256x256  256x256  256 and 1  For example  IPv4 address   127 0 0 1 32 bit number     127x256 3     0x256 2     0x256 1    1   2130706433

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The reverse of Davy Landman s function  string IntToIp int d      int v1   d  amp  0xff    int v2    d  gt  gt  8   amp  0xff    int v3    d  gt  gt  16   amp  0xff    int v4    d  gt  gt  24     return v4         v3         v2         v1

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Assuming you have an IP Address in string format  eg  254 254 254 254   string   vals   inVal Split       uint output   0  for  byte i   0  i  lt  vals Length  i    output     uint  byte Parse vals i    lt  lt  8    vals GetUpperBound 0  - i

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Davy Ladman your solution with shift are corrent but only for ip starting with number less or equal 99  infact first octect must be cast up to long   Anyway convert back with long type is quite difficult because store 64 bit  not 32 for Ip  and fill 4 bytes with zeroes  static uint ToInt string addr       return BitConverter ToUInt32 IPAddress Parse addr  GetAddressBytes    0      static string ToAddr uint address        return new IPAddress address  ToString        Enjoy   Massimo

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Here s a pair of methods to convert from IPv4 to a correct integer and back   public static uint ConvertFromIpAddressToInteger string ipAddress        var address   IPAddress Parse ipAddress       byte   bytes   address GetAddressBytes            flip big-endian network order  to little-endian     if  BitConverter IsLittleEndian                Array Reverse bytes              return BitConverter ToUInt32 bytes  0      public static string ConvertFromIntegerToIpAddress uint ipAddress        byte   bytes   BitConverter GetBytes ipAddress           flip little-endian to big-endian network order      if  BitConverter IsLittleEndian                Array Reverse bytes              return new IPAddress bytes  ToString        Example  ConvertFromIpAddressToInteger  255 255 255 254       4294967294 ConvertFromIntegerToIpAddress 4294967294      255 255 255 254   Explanation  IP addresses are in network order  big-endian   while ints are little-endian on Windows  so to get a correct value  you must reverse the bytes before converting on a little-endian system   Also  even for IPv4  an int can t hold addresses bigger than 127 255 255 255  e g  the broadcast address  255 255 255 255   so use a uint

User · Answer

Take a look at some of the crazy parsing examples in  Net s IPAddress Parse   MSDN    65536      0 0 255 255  20 2      20 0 0 2  20 65535      20 0 255 255  128 1 2      128 1 0 2

User · Answer

public static Int32 getLongIPAddress string ipAddress                return IPAddress NetworkToHostOrder BitConverter ToInt32 IPAddress Parse ipAddress  GetAddressBytes    0            The above example would be the way I go    Only thing you might have to do is convert to a UInt32 for display purposes  or string purposes including using it as a long address in string form   Which is what is needed when using the IPAddress Parse String  function   Sigh

[c#] How to convert an IPv4 address into a integer in C#?

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