C # How to obtain a real IP Address,

C # How to obtain a real IP Address,

The common method for getting user IP addresses is

C # code Replication

  string IpAddress = "";if((HttpContext.Current.Request.ServerVariables["HTTP_X_FORWARDED_FOR"]!=null && HttpContext.Current.Request.ServerVariables["HTTP_X_FORWARDED_FOR"] !=String.Empty) ){        IpAddress=HttpContext.Current.Request.ServerVariables["HTTP_X_FORWARDED_FOR"] ;}else{         HttpContext.Current.Request.ServerVariables["REMOTE_ADDR"]; }

In fact, the above Code only tries to use a layer-1 proxy with the user. if the user has a layer-2, layer-3 HTTP_X_FORWARDED_FOR value is: "The real IP address of the Local Machine, layer-1 proxy IP address, layer-2 proxy IP address ,..... ", if the length of the IP field stored in your data is very small (15 bytes), the database reports an error.

In practice, there are few users who use multi-layer transparent proxy.

 

 

How to obtain the real IP address of a user

 

C # code Replication

Using System; using System. data; using System. configuration; using System. web; using System. web. security; using System. web. UI; using System. web. UI. webControls; using System. web. UI. webControls. webParts; using System. web. UI. htmlControls; using System. text. regularExpressions; namespace Common {/// <summary> // summary of IPAddress /// </summary> public class IPAddress: System. web. UI. page {public static Int64 toDena RyIp (string ip) {Int64 _ Int64 = 0; string _ ip = ip; if (_ ip. lastIndexOf (". ")>-1) {string [] _ iparray = _ ip. split ('. '); _ Int64 = Int64.Parse (_ iparray. getValue (0 ). toString () * 256*256*256 + Int64.Parse (_ iparray. getValue (1 ). toString () * 256*256 + Int64.Parse (_ iparray. getValue (2 ). toString () * 256 + Int64.Parse (_ iparray. getValue (3 ). toString ()-1;} retur N _ Int64;} // <summary> /// ip decimal // </summary> public static Int64 DenaryIp {get {Int64 _ Int64 = 0; string _ ip = IP; if (_ ip. lastIndexOf (". ")>-1) {string [] _ iparray = _ ip. split ('. '); _ Int64 = Int64.Parse (_ iparray. getValue (0 ). toString () * 256*256*256 + Int64.Parse (_ iparray. getValue (1 ). toString () * 256*256 + Int64.Parse (_ iparray. getValue (2 ). toString () * 25 6 + Int64.Parse (_ iparray. getValue (3 ). toString ()-1;} return _ Int64;} public static string IP {get {string result = String. empty; result = HttpContext. current. request. serverVariables ["HTTP_X_FORWARDED_FOR"]; if (result! = Null & result! = String. empty) {// There may be proxy if (result. indexOf (". ") =-1) // No ". "Definitely not IPv4 format result = null; else {if (result. indexOf (",")! =-1) {// There are ",", multiple proxies are estimated. Obtain the first IP address that is not an intranet IP address. Result = result. replace ("",""). replace ("", ""); string [] temparyip = result. split (",;". toCharArray (); for (int I = 0; I <temparyip. length; I ++) {if (IsIPAddress (temparyip [I]) & temparyip [I]. substring (0, 3 )! = "10." & temparyip [I]. Substring (0, 7 )! = "192.168" & temparyip [I]. Substring (0, 7 )! = "1. 172.16. ") {return temparyip [I]; // find the address that is not the Intranet address} else if (IsIPAddress (result) // The proxy is the return result in IP format; else result = null; // the content in the proxy is not an IP address, take IP} string IpAddress = (HttpContext. current. request. serverVariables ["HTTP_X_FORWARDED_FOR"]! = Null & HttpContext. Current. Request. ServerVariables ["HTTP_X_FORWARDED_FOR"]! = String. empty) HttpContext. current. request. serverVariables ["HTTP_X_FORWARDED_FOR"]: HttpContext. current. request. serverVariables ["REMOTE_ADDR"]; if (null = result | result = String. empty) result = HttpContext. current. request. serverVariables ["REMOTE_ADDR"]; if (result = null | result = String. empty) result = HttpContext. current. request. userHostAddress; return result ;}}// whether the ip address format is public static bool IsIPAddress (string str1) {if (str1 = null | str1 = string. empty | str1.Length <7 | str1.Length> 15) return false; string regformat = @ "^ \ d {1, 3} [\.] \ d {1, 3} [\.] \ d {1, 3} [\.] \ d {1, 3} $ "; Regex regex = new Regex (regformat, RegexOptions. ignoreCase); return regex. isMatch (str1 );}}}

A simple program of C language Bubble Sorting

Main ()
{
Int I, j, temp;
Int a [10];
For (I = 0; I <10; I ++)
Scanf ("% d,", & a [I]);
For (j = 0; j <= 9; j ++)
{For (I = 0; I <10-j; I ++)
If (a [I]> a [I + 1])
{Temp = a [I];
A [I] = a [I + 1];
A [I + 1] = temp ;}
}
For (I = 1; I <11; I ++)
Printf ("% 5d,", a [I]);
Printf ("\ n ");
}

--------------
Bubble Algorithm
Algorithm Analysis and Improvement of Bubble Sorting
The basic idea of exchanging sorting is to compare the keywords of the records to be sorted in pairs. If the order of the two records is the opposite, the two records are exchanged until there is no reverse order record.
The basic concepts of application exchange sorting include Bubble sorting and quick sorting.

Bubble Sorting

1. Sorting Method
Vertically arrange the sorted record array R [1. n]. Each record R is considered as a bubble with the weight of R. key. According to the principle that a Light Bubble cannot be under a heavy bubble, scan the array R from the bottom up: Any Light Bubble scanned to a violation of this principle will make it "float" up ". This is repeated until the last two bubbles are light and heavy.
(1) initial
R [1. n] is an unordered area.

(2) First scan
The weights of two adjacent bubbles are compared from the bottom of the unordered area to the top. If the light bubbles are found to be in the lower and severe bubbles, the positions of the two bubbles are exchanged. That is, compare (R [n], R [n-1]), (R [n-1], R [N-2]),…, (R [2], R [1]); for each pair of bubbles (R [j + 1], R [j]), if R [j + 1]. key <R [j]. key, then the contents of R [j + 1] and R [j] are exchanged.
When the first scan is complete, the "lightest" bubble floated to the top of the interval, that is, the record with the smallest keyword is placed on the highest position R [1.

(3) second scan
Scan R [2. n]. When scanning is completed, the "light" bubble floated to the R [2] position ......
Finally, the sequential area R [1. n] can be obtained through n-1 scanning.
Note:
During the I-trip scan, R [1 .. I-1] and R [I.. n] are the current sequential and disordered areas, respectively. The scan continues from the bottom of the unordered area to the top of the area. When scanning is completed, the shortest bubbles in the area float to the top position R. The result is that R [1. I] is changed to a new ordered area.

2. Bubble sorting process example
Bubble Sorting of files whose keyword sequence is 49 38 65 97 76 13 27 49

3. Sorting Algorithm
(1) Analysis
Because each sort adds a bubble to the ordered area, there are n-1 bubbles in the ordered area after N-1 sort, in the disordered area, the bubble weight is always greater than or equal to the bubble weight in the ordered area. Therefore, the entire Bubble sorting process requires at most n-1 sorting.
If no bubble position exchange is found in a sorting, it means that all bubbles in the unordered area to be sorted meet the principle of being light and heavy. Therefore, the Bubble sorting process can be terminated after this sorting. Therefore, in the following algorithm, a Boolean exchange is introduced, which is set to FALSE before each sort starts. If an exchange occurs during the sorting process, set it to TRUE. Check exchange at the end of sorting. If exchange has not occurred, terminate the algorithm and no longer perform the next sorting.

(2) specific algorithms
Void BubbleSort (SeqList R)
{// R (l. n) is the file to be sorted. It uses bottom-up scanning to perform Bubble Sorting on R.
Int I, j;
Boolean exchange; // exchange flag
For (I = 1; I <G id = "1">

A simple program of C language Bubble Sorting

Main ()
{
Int I, j, temp;
Int a [10];
For (I = 0; I <10; I ++)
Scanf ("% d,", & a [I]);
For (j = 0; j <= 9; j ++)
{For (I = 0; I <10-j; I ++)
If (a [I]> a [I + 1])
{Temp = a [I];
A [I] = a [I + 1];
A [I + 1] = temp ;}
}
For (I = 1; I <11; I ++)
Printf ("% 5d,", a [I]);
Printf ("\ n ");
}

--------------
Bubble Algorithm
Algorithm Analysis and Improvement of Bubble Sorting
The basic idea of exchanging sorting is to compare the keywords of the records to be sorted in pairs. If the order of the two records is the opposite, the two records are exchanged until there is no reverse order record.
The basic concepts of application exchange sorting include Bubble sorting and quick sorting.

Bubble Sorting

1. Sorting Method
Vertically arrange the sorted record array R [1. n]. Each record R is considered as a bubble with the weight of R. key. According to the principle that a Light Bubble cannot be under a heavy bubble, scan the array R from the bottom up: Any Light Bubble scanned to a violation of this principle will make it "float" up ". This is repeated until the last two bubbles are light and heavy.
(1) initial
R [1. n] is an unordered area.

(2) First scan
The weights of two adjacent bubbles are compared from the bottom of the unordered area to the top. If the light bubbles are found to be in the lower and severe bubbles, the positions of the two bubbles are exchanged. That is, compare (R [n], R [n-1]), (R [n-1], R [N-2]),…, (R [2], R [1]); for each pair of bubbles (R [j + 1], R [j]), if R [j + 1]. key <R [j]. key, then the contents of R [j + 1] and R [j] are exchanged.
When the first scan is complete, the "lightest" bubble floated to the top of the interval, that is, the record with the smallest keyword is placed on the highest position R [1.

(3) second scan
Scan R [2. n]. When scanning is completed, the "light" bubble floated to the R [2] position ......
Finally, the sequential area R [1. n] can be obtained through n-1 scanning.
Note:
During the I-trip scan, R [1 .. I-1] and R [I.. n] are the current sequential and disordered areas, respectively. The scan continues from the bottom of the unordered area to the top of the area. When scanning is completed, the shortest bubbles in the area float to the top position R. The result is that R [1. I] is changed to a new ordered area.

2. Bubble sorting process example
Bubble Sorting of files whose keyword sequence is 49 38 65 97 76 13 27 49

3. Sorting Algorithm
(1) Analysis
Because each sort adds a bubble to the ordered area, there are n-1 bubbles in the ordered area after N-1 sort, in the disordered area, the bubble weight is always greater than or equal to the bubble weight in the ordered area. Therefore, the entire Bubble sorting process requires at most n-1 sorting.
If no bubble position exchange is found in a sorting, it means that all bubbles in the unordered area to be sorted meet the principle of being light and heavy. Therefore, the Bubble sorting process can be terminated after this sorting. Therefore, in the following algorithm, a Boolean exchange is introduced, which is set to FALSE before each sort starts. If an exchange occurs during the sorting process, set it to TRUE. Check exchange at the end of sorting. If exchange has not occurred, terminate the algorithm and no longer perform the next sorting.

(2) specific algorithms
Void BubbleSort (SeqList R)
{// R (l. n) is the file to be sorted. It uses bottom-up scanning to perform Bubble Sorting on R.
Int I, j;
Boolean exchange; // exchange flag
For (I = 1; I <G id = "1">