How can I detect the encoding codepage of a text file

Question

In our application  we receive text files   txt   csv  etc   from diverse sources  When reading  these files sometimes contain garbage  because the files where created in a different unknown codepage   Is there a way to  automatically  detect the codepage of a text file    The detectEncodingFromByteOrderMarks  on the StreamReader constructor  works for UTF8  and other unicode marked files  but I m looking for a way to detect code pages  like ibm850  windows1252      Thanks for your answers  this is what I ve done   The files we receive are from end-users  they do not have a clue about codepages  The receivers are also end-users  by now this is what they know about codepages  Codepages exist  and are annoying   Solution     Open the received file in Notepad  look at a garbled piece of text  If somebody is called Fran  ois or something  with your human intelligence you can guess this  I ve created a small app that the user can use to open the file with  and enter a text that user knows it will appear in the file  when the correct codepage is used   Loop through all codepages  and display the ones that give a solution with the user provided text   If more as one codepage pops up  ask the user to specify more text

User · Accepted Answer

You can t detect the codepage  you need to be told it  You can analyse the bytes and guess it  but that can give some bizarre  sometimes amusing  results  I can t find it now  but I m sure Notepad can be tricked into displaying English text in Chinese    Anyway  this is what you need to read   The Absolute Minimum Every Software Developer Absolutely  Positively Must Know About Unicode and Character Sets  No Excuses     Specifically Joel says      The Single Most Important Fact About Encodings      If you completely forget everything I just explained  please remember one extremely important fact  It does not make sense to have a string without knowing what encoding it uses  You can no longer stick your head in the sand and pretend that  plain  text is ASCII    There Ain t No Such Thing As Plain Text       If you have a string  in memory  in a file  or in an email message  you have to know what encoding it is in or you cannot interpret it or display it to users correctly

User · Answer

If someone is looking for a 93 9  solution  This works for me   public static class StreamExtension            lt summary gt          Convert the content to a string           lt  summary gt           lt param name  stream  gt The stream  lt  param gt           lt returns gt  lt  returns gt      public static string ReadAsString this Stream stream                var startPosition   stream Position          try                          1  Check for a BOM                2  or try with UTF-8  The most  86 3   used encoding  Visit  http   w3techs com technologies overview character encoding all              var streamReader   new StreamReader stream  new UTF8Encoding encoderShouldEmitUTF8Identifier  false  throwOnInvalidBytes  true   detectEncodingFromByteOrderMarks  true               return streamReader ReadToEnd                      catch  DecoderFallbackException ex                        stream Position   startPosition                  3  The second most  6 7   used encoding is ISO-8859-1  So use Windows-1252  0 9   also know as ANSI   which is a superset of ISO-8859-1              var streamReader   new StreamReader stream  Encoding GetEncoding 1252                return streamReader ReadToEnd

User · Answer

If you re looking to detect non-UTF encodings  i e  no BOM   you re basically down to heuristics and statistical analysis of the text  You might want to take a look at the Mozilla paper on universal charset detection  same link  with better formatting via Wayback Machine

User · Answer

If you re looking to detect non-UTF encodings  i e  no BOM   you re basically down to heuristics and statistical analysis of the text  You might want to take a look at the Mozilla paper on universal charset detection  same link  with better formatting via Wayback Machine

User · Answer

The tool  uchardet  does this well using character frequency distribution models for each charset    Larger files and more  typical  files have more confidence  obviously    On ubuntu  you just apt-get install uchardet      On other systems  get the source  usage  amp  docs here  https   github com BYVoid uchardet

User · Answer

Since it basically comes down to heuristics  it may help to use the encoding of previously received files from the same source as a first hint   Most people  or applications  do stuff in pretty much the same order every time  often on the same machine  so its quite likely that when Bob creates a  csv file and sends it to Mary it ll always be using Windows-1252 or whatever his machine defaults to   Where possible a bit of customer training never hurts either  -

User · Answer

I use this code to detect Unicode and windows default ansi codepage when reading a file  For other codings a check of content is necessary  manually or by programming  This can de used to save the text with the same encoding as when it was opened   I use VB NET    Works for Default and unicode  auto detect  Dim mystreamreader As New StreamReader LocalFileName  Encoding Default   MyEditTextBox Text   mystreamreader ReadToEnd   Debug Print mystreamreader CurrentEncoding CodePage   Autodetected encoding mystreamreader Close

User · Answer

You can t detect the codepage   This is clearly false  Every web browser has some kind of universal charset detector to deal with pages which have no indication whatsoever of an encoding  Firefox has one  You can download the code and see how it does it  See some documentation here  Basically  it is a heuristic  but one that works really well   Given a reasonable amount of text  it is even possible to detect the language   Here s another one I just found using Google

User · Answer

I ve done something similar in Python  Basically  you need lots of sample data from various encodings  which are broken down by a sliding two-byte window and stored in a dictionary  hash   keyed on byte-pairs providing values of lists of encodings   Given that dictionary  hash   you take your input text and    if it starts with any BOM character    xfe xff  for UTF-16-BE    xff xfe  for UTF-16-LE    xef xbb xbf  for UTF-8 etc   I treat it as suggested if not  then take a large enough sample of the text  take all byte-pairs of the sample and choose the encoding that is the least common suggested from the dictionary    If you ve also sampled UTF encoded texts that do not start with any BOM  the second step will cover those that slipped from the first step   So far  it works for me  the sample data and subsequent input data are subtitles in various languages  with diminishing error rates

User · Answer

Thanks  Erik Aronesty for mentioning uchardet  Meanwhile the  same   tool exists for linux  chardet  Or  on cygwin you may want to use  chardetect   See  chardet man page  https   www commandlinux com man-page man1 chardetect 1 html  This will heuristically detect  guess  the character encoding for each given file and will report the name and confidence level for each file s detected character encoding

User · Answer

Notepad    has this feature out-of-the-box  It also supports changing it

User · Answer

I was actually looking for a generic  not programming way of detecting the file encoding  but I didn t find that yet  What I did find by testing with different encodings was that my text was UTF-7   So where I first was doing  StreamReader file   File OpenText fullfilename    I had to change it to  StreamReader file   new StreamReader fullfilename  System Text Encoding UTF7    OpenText assumes it s UTF-8   you can also create the StreamReader like this new StreamReader fullfilename  true   the second parameter meaning that it should try and detect the encoding from the byteordermark of the file  but that didn t work in my case

User · Answer

10Y     had passed since this was asked  and still I see no mention of MS s good  non-GPL ed solution  IMultiLanguage2 API   Most libraries already mentioned are based on Mozilla s UDE - and it seems reasonable that browsers have already tackled similar problems  I don t know what is chrome s solution  but since IE 5 0  MS have released theirs  and it is    Free of GPL-and-the-like licensing issues  Backed and maintained probably forever  Gives rich output - all valid candidates for encoding codepages along with confidence scores  Surprisingly easy to use  it is a single function call     It is a native COM call  but here s some very nice work by Carsten Zeumer  that handles the interop mess for  net usage  There are some others around  but by and large this library doesn t get the attention it deserves

User · Answer

Since it basically comes down to heuristics  it may help to use the encoding of previously received files from the same source as a first hint   Most people  or applications  do stuff in pretty much the same order every time  often on the same machine  so its quite likely that when Bob creates a  csv file and sends it to Mary it ll always be using Windows-1252 or whatever his machine defaults to   Where possible a bit of customer training never hurts either  -

User · Answer

If you re looking to detect non-UTF encodings  i e  no BOM   you re basically down to heuristics and statistical analysis of the text  You might want to take a look at the Mozilla paper on universal charset detection  same link  with better formatting via Wayback Machine

User · Answer

Have you tried C  port for Mozilla Universal Charset Detector  Example from http   code google com p ude   public static void Main String   args        string filename   args 0       using  FileStream fs   File OpenRead filename             Ude CharsetDetector cdet   new Ude CharsetDetector            cdet Feed fs           cdet DataEnd            if  cdet Charset    null                Console WriteLine  Charset   0   confidence   1                      cdet Charset  cdet Confidence             else               Console WriteLine  Detection failed

User · Answer

Open file in AkelPad or just copy paste a garbled text   go to Edit -  Selection -  Recode    -  check  Autodetect

User · Answer

Have you tried C  port for Mozilla Universal Charset Detector  Example from http   code google com p ude   public static void Main String   args        string filename   args 0       using  FileStream fs   File OpenRead filename             Ude CharsetDetector cdet   new Ude CharsetDetector            cdet Feed fs           cdet DataEnd            if  cdet Charset    null                Console WriteLine  Charset   0   confidence   1                      cdet Charset  cdet Confidence             else               Console WriteLine  Detection failed

User · Answer

Thanks  Erik Aronesty for mentioning uchardet  Meanwhile the  same   tool exists for linux  chardet  Or  on cygwin you may want to use  chardetect   See  chardet man page  https   www commandlinux com man-page man1 chardetect 1 html  This will heuristically detect  guess  the character encoding for each given file and will report the name and confidence level for each file s detected character encoding

User · Answer

Notepad    has this feature out-of-the-box  It also supports changing it

User · Answer

As addon to ITmeze post  I ve used this function to convert the output of C  port for Mozilla Universal Charset Detector      private Encoding GetEncodingFromString string codePageName                try                       return Encoding GetEncoding codePageName                     catch                       return Encoding ASCII                    MSDN

User · Answer

As addon to ITmeze post  I ve used this function to convert the output of C  port for Mozilla Universal Charset Detector      private Encoding GetEncodingFromString string codePageName                try                       return Encoding GetEncoding codePageName                     catch                       return Encoding ASCII                    MSDN

User · Answer

I know it s very late for this question and this solution won t appeal to some  because of its english-centric bias and its lack of statistical empirical testing   but it s worked very well for me  especially for processing uploaded CSV data   http   www architectshack com TextFileEncodingDetector ashx  Advantages    BOM detection built-in Default fallback encoding customizable pretty reliable  in my experience  for western-european-based files containing some exotic data  eg french names  with a mixture of UTF-8 and Latin-1-style files - basically the bulk of US and western european environments    Note  I m the one who wrote this class  so obviously take it with a grain of salt

User · Answer

I ve done something similar in Python  Basically  you need lots of sample data from various encodings  which are broken down by a sliding two-byte window and stored in a dictionary  hash   keyed on byte-pairs providing values of lists of encodings   Given that dictionary  hash   you take your input text and    if it starts with any BOM character    xfe xff  for UTF-16-BE    xff xfe  for UTF-16-LE    xef xbb xbf  for UTF-8 etc   I treat it as suggested if not  then take a large enough sample of the text  take all byte-pairs of the sample and choose the encoding that is the least common suggested from the dictionary    If you ve also sampled UTF encoded texts that do not start with any BOM  the second step will cover those that slipped from the first step   So far  it works for me  the sample data and subsequent input data are subtitles in various languages  with diminishing error rates

User · Answer

Looking for different solution  I found that   https   code google com p ude   this solution is kinda heavy   I needed some basic encoding detection  based on 4 first bytes and probably xml charset detection - so I ve took some sample source code from internet and added slightly modified version of  http   lists w3 org Archives Public www-validator 2002Aug 0084 html  written for Java       public static Encoding DetectEncoding byte   fileContent                if  fileContent    null              throw new ArgumentNullException             if  fileContent Length  lt  2              return Encoding ASCII          Default fallback          if  fileContent 0     0xff              amp  amp  fileContent 1     0xfe              amp  amp   fileContent Length  lt  4                    fileContent 2     0                    fileContent 3     0                                             return Encoding Unicode           if  fileContent 0     0xfe              amp  amp  fileContent 1     0xff                           return Encoding BigEndianUnicode           if  fileContent Length  lt  3              return null           if  fileContent 0     0xef  amp  amp  fileContent 1     0xbb  amp  amp  fileContent 2     0xbf              return Encoding UTF8           if  fileContent 0     0x2b  amp  amp  fileContent 1     0x2f  amp  amp  fileContent 2     0x76              return Encoding UTF7           if  fileContent Length  lt  4              return null           if  fileContent 0     0xff  amp  amp  fileContent 1     0xfe  amp  amp  fileContent 2     0  amp  amp  fileContent 3     0              return Encoding UTF32           if  fileContent 0     0  amp  amp  fileContent 1     0  amp  amp  fileContent 2     0xfe  amp  amp  fileContent 3     0xff              return Encoding GetEncoding 12001            String probe          int len   fileContent Length           if  fileContent Length  gt   128   len   128          probe   Encoding ASCII GetString fileContent  0  len            MatchCollection mc   Regex Matches probe     lt    xml   lt  gt   encoding    t  n  r      t  n  r         A-Za-z   A-Za-z0-9    -      RegexOptions Singleline              Add   0  Groups 1  Value  to the end to test regex          if  mc Count    1  amp  amp  mc 0  Groups Count  gt   2                            Typically picks up  UTF-8  string             Encoding enc   null               try                   enc   Encoding GetEncoding  mc 0  Groups 1  Value                 catch  Exception                    if  enc    null                   return enc                     return Encoding ASCII          Default fallback         It s enough to read probably first 1024 bytes from file  but I m loading whole file

User · Answer

I was actually looking for a generic  not programming way of detecting the file encoding  but I didn t find that yet  What I did find by testing with different encodings was that my text was UTF-7   So where I first was doing  StreamReader file   File OpenText fullfilename    I had to change it to  StreamReader file   new StreamReader fullfilename  System Text Encoding UTF7    OpenText assumes it s UTF-8   you can also create the StreamReader like this new StreamReader fullfilename  true   the second parameter meaning that it should try and detect the encoding from the byteordermark of the file  but that didn t work in my case

User · Answer

If you can link to a C library  you can use libenca   See http   cihar com software enca    From the man page      Enca reads given text files  or standard input when none are given    and uses knowledge about their language  must be supported by you  and   a mixture of parsing  statistical analysis  guessing and black magic   to determine their encodings    It s GPL v2

User · Answer

Since it basically comes down to heuristics  it may help to use the encoding of previously received files from the same source as a first hint   Most people  or applications  do stuff in pretty much the same order every time  often on the same machine  so its quite likely that when Bob creates a  csv file and sends it to Mary it ll always be using Windows-1252 or whatever his machine defaults to   Where possible a bit of customer training never hurts either  -

User · Answer

10Y     had passed since this was asked  and still I see no mention of MS s good  non-GPL ed solution  IMultiLanguage2 API   Most libraries already mentioned are based on Mozilla s UDE - and it seems reasonable that browsers have already tackled similar problems  I don t know what is chrome s solution  but since IE 5 0  MS have released theirs  and it is    Free of GPL-and-the-like licensing issues  Backed and maintained probably forever  Gives rich output - all valid candidates for encoding codepages along with confidence scores  Surprisingly easy to use  it is a single function call     It is a native COM call  but here s some very nice work by Carsten Zeumer  that handles the interop mess for  net usage  There are some others around  but by and large this library doesn t get the attention it deserves

User · Answer

Got the same problem but didn t found a good solution yet for detecting it automatically   Now im using PsPad  www pspad com  for that    Works fine

User · Answer

I ve done something similar in Python  Basically  you need lots of sample data from various encodings  which are broken down by a sliding two-byte window and stored in a dictionary  hash   keyed on byte-pairs providing values of lists of encodings   Given that dictionary  hash   you take your input text and    if it starts with any BOM character    xfe xff  for UTF-16-BE    xff xfe  for UTF-16-LE    xef xbb xbf  for UTF-8 etc   I treat it as suggested if not  then take a large enough sample of the text  take all byte-pairs of the sample and choose the encoding that is the least common suggested from the dictionary    If you ve also sampled UTF encoded texts that do not start with any BOM  the second step will cover those that slipped from the first step   So far  it works for me  the sample data and subsequent input data are subtitles in various languages  with diminishing error rates

User · Answer

Got the same problem but didn t found a good solution yet for detecting it automatically   Now im using PsPad  www pspad com  for that    Works fine

User · Answer

If you can link to a C library  you can use libenca   See http   cihar com software enca    From the man page      Enca reads given text files  or standard input when none are given    and uses knowledge about their language  must be supported by you  and   a mixture of parsing  statistical analysis  guessing and black magic   to determine their encodings    It s GPL v2

User · Answer

The StreamReader class s constructor takes a  detect encoding  parameter

User · Answer

Got the same problem but didn t found a good solution yet for detecting it automatically   Now im using PsPad  www pspad com  for that    Works fine

User · Answer

I ve done something similar in Python  Basically  you need lots of sample data from various encodings  which are broken down by a sliding two-byte window and stored in a dictionary  hash   keyed on byte-pairs providing values of lists of encodings   Given that dictionary  hash   you take your input text and    if it starts with any BOM character    xfe xff  for UTF-16-BE    xff xfe  for UTF-16-LE    xef xbb xbf  for UTF-8 etc   I treat it as suggested if not  then take a large enough sample of the text  take all byte-pairs of the sample and choose the encoding that is the least common suggested from the dictionary    If you ve also sampled UTF encoded texts that do not start with any BOM  the second step will cover those that slipped from the first step   So far  it works for me  the sample data and subsequent input data are subtitles in various languages  with diminishing error rates

User · Answer

Looking for different solution  I found that   https   code google com p ude   this solution is kinda heavy   I needed some basic encoding detection  based on 4 first bytes and probably xml charset detection - so I ve took some sample source code from internet and added slightly modified version of  http   lists w3 org Archives Public www-validator 2002Aug 0084 html  written for Java       public static Encoding DetectEncoding byte   fileContent                if  fileContent    null              throw new ArgumentNullException             if  fileContent Length  lt  2              return Encoding ASCII          Default fallback          if  fileContent 0     0xff              amp  amp  fileContent 1     0xfe              amp  amp   fileContent Length  lt  4                    fileContent 2     0                    fileContent 3     0                                             return Encoding Unicode           if  fileContent 0     0xfe              amp  amp  fileContent 1     0xff                           return Encoding BigEndianUnicode           if  fileContent Length  lt  3              return null           if  fileContent 0     0xef  amp  amp  fileContent 1     0xbb  amp  amp  fileContent 2     0xbf              return Encoding UTF8           if  fileContent 0     0x2b  amp  amp  fileContent 1     0x2f  amp  amp  fileContent 2     0x76              return Encoding UTF7           if  fileContent Length  lt  4              return null           if  fileContent 0     0xff  amp  amp  fileContent 1     0xfe  amp  amp  fileContent 2     0  amp  amp  fileContent 3     0              return Encoding UTF32           if  fileContent 0     0  amp  amp  fileContent 1     0  amp  amp  fileContent 2     0xfe  amp  amp  fileContent 3     0xff              return Encoding GetEncoding 12001            String probe          int len   fileContent Length           if  fileContent Length  gt   128   len   128          probe   Encoding ASCII GetString fileContent  0  len            MatchCollection mc   Regex Matches probe     lt    xml   lt  gt   encoding    t  n  r      t  n  r         A-Za-z   A-Za-z0-9    -      RegexOptions Singleline              Add   0  Groups 1  Value  to the end to test regex          if  mc Count    1  amp  amp  mc 0  Groups Count  gt   2                            Typically picks up  UTF-8  string             Encoding enc   null               try                   enc   Encoding GetEncoding  mc 0  Groups 1  Value                 catch  Exception                    if  enc    null                   return enc                     return Encoding ASCII          Default fallback         It s enough to read probably first 1024 bytes from file  but I m loading whole file

User · Answer

Open file in AkelPad or just copy paste a garbled text   go to Edit -  Selection -  Recode    -  check  Autodetect

User · Answer

I use this code to detect Unicode and windows default ansi codepage when reading a file  For other codings a check of content is necessary  manually or by programming  This can de used to save the text with the same encoding as when it was opened   I use VB NET    Works for Default and unicode  auto detect  Dim mystreamreader As New StreamReader LocalFileName  Encoding Default   MyEditTextBox Text   mystreamreader ReadToEnd   Debug Print mystreamreader CurrentEncoding CodePage   Autodetected encoding mystreamreader Close

User · Answer

If you re looking to detect non-UTF encodings  i e  no BOM   you re basically down to heuristics and statistical analysis of the text  You might want to take a look at the Mozilla paper on universal charset detection  same link  with better formatting via Wayback Machine

User · Answer

You can t detect the codepage   This is clearly false  Every web browser has some kind of universal charset detector to deal with pages which have no indication whatsoever of an encoding  Firefox has one  You can download the code and see how it does it  See some documentation here  Basically  it is a heuristic  but one that works really well   Given a reasonable amount of text  it is even possible to detect the language   Here s another one I just found using Google

User · Answer

If someone is looking for a 93 9  solution  This works for me   public static class StreamExtension            lt summary gt          Convert the content to a string           lt  summary gt           lt param name  stream  gt The stream  lt  param gt           lt returns gt  lt  returns gt      public static string ReadAsString this Stream stream                var startPosition   stream Position          try                          1  Check for a BOM                2  or try with UTF-8  The most  86 3   used encoding  Visit  http   w3techs com technologies overview character encoding all              var streamReader   new StreamReader stream  new UTF8Encoding encoderShouldEmitUTF8Identifier  false  throwOnInvalidBytes  true   detectEncodingFromByteOrderMarks  true               return streamReader ReadToEnd                      catch  DecoderFallbackException ex                        stream Position   startPosition                  3  The second most  6 7   used encoding is ISO-8859-1  So use Windows-1252  0 9   also know as ANSI   which is a superset of ISO-8859-1              var streamReader   new StreamReader stream  Encoding GetEncoding 1252                return streamReader ReadToEnd

User · Answer

Got the same problem but didn t found a good solution yet for detecting it automatically   Now im using PsPad  www pspad com  for that    Works fine

User · Answer

Since it basically comes down to heuristics  it may help to use the encoding of previously received files from the same source as a first hint   Most people  or applications  do stuff in pretty much the same order every time  often on the same machine  so its quite likely that when Bob creates a  csv file and sends it to Mary it ll always be using Windows-1252 or whatever his machine defaults to   Where possible a bit of customer training never hurts either  -

User · Answer

You can t detect the codepage   This is clearly false  Every web browser has some kind of universal charset detector to deal with pages which have no indication whatsoever of an encoding  Firefox has one  You can download the code and see how it does it  See some documentation here  Basically  it is a heuristic  but one that works really well   Given a reasonable amount of text  it is even possible to detect the language   Here s another one I just found using Google

User · Answer

You can t detect the codepage   This is clearly false  Every web browser has some kind of universal charset detector to deal with pages which have no indication whatsoever of an encoding  Firefox has one  You can download the code and see how it does it  See some documentation here  Basically  it is a heuristic  but one that works really well   Given a reasonable amount of text  it is even possible to detect the language   Here s another one I just found using Google

User · Answer

The StreamReader class s constructor takes a  detect encoding  parameter

User · Answer

The StreamReader class s constructor takes a  detect encoding  parameter

User · Answer

The tool  uchardet  does this well using character frequency distribution models for each charset    Larger files and more  typical  files have more confidence  obviously    On ubuntu  you just apt-get install uchardet      On other systems  get the source  usage  amp  docs here  https   github com BYVoid uchardet

User · Answer

I know it s very late for this question and this solution won t appeal to some  because of its english-centric bias and its lack of statistical empirical testing   but it s worked very well for me  especially for processing uploaded CSV data   http   www architectshack com TextFileEncodingDetector ashx  Advantages    BOM detection built-in Default fallback encoding customizable pretty reliable  in my experience  for western-european-based files containing some exotic data  eg french names  with a mixture of UTF-8 and Latin-1-style files - basically the bulk of US and western european environments    Note  I m the one who wrote this class  so obviously take it with a grain of salt

User · Answer

The StreamReader class s constructor takes a  detect encoding  parameter

[c#] How can I detect the encoding/codepage of a text file

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