Reading CSV file and storing values into an array

Question

I am trying to read a   csv-file   The   csv-file consist of two columns separated by semicolon          I am able to read the   csv-file using StreamReader and able to separate each line by using the Split   function  I want to store each column into a separate array and then display it    Is it possible to do that

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You can use Microsoft VisualBasic FileIO TextFieldParser dll in C  for better performance   get below code example from above article  static void Main         string csv file path   C  Users Administrator Desktop test csv        DataTable csvData   GetDataTabletFromCSVFile csv file path        Console WriteLine  Rows count     csvData Rows Count        Console ReadLine        private static DataTable GetDataTabletFromCSVFile string csv file path        DataTable csvData   new DataTable         try            using TextFieldParser csvReader   new TextFieldParser csv file path                         csvReader SetDelimiters new string                         csvReader HasFieldsEnclosedInQuotes   true              string   colFields   csvReader ReadFields                foreach  string column in colFields                                DataColumn datecolumn   new DataColumn column                   datecolumn AllowDBNull   true                  csvData Columns Add datecolumn                              while   csvReader EndOfData                                string   fieldData   csvReader ReadFields                      Making empty value as null                 for  int i   0  i  lt  fieldData Length  i                                          if  fieldData i                                                       fieldData i    null                                                          csvData Rows Add fieldData                                     catch  Exception ex                  return csvData

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var firstColumn   new List lt string gt     var lastColumn   new List lt string gt         your code for reading CSV file  foreach var line in file        var array   line Split           firstColumn Add array 0        lastColumn Add array 1       var firstArray   firstColumn ToArray    var lastArray   lastColumn ToArray

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You can t create an array immediately because you need to know the number of rows from the beginning  and this would require to read the csv file twice   You can store values in two List lt T gt  and then use them or convert into an array using List lt T gt  ToArray    Very simple example   var column1   new List lt string gt     var column2   new List lt string gt     using  var rd   new StreamReader  filename csv          while   rd EndOfStream                var splits   rd ReadLine   Split               column1 Add splits 0            column2 Add splits 1               print column1 Console WriteLine  Column 1     foreach  var element in column1      Console WriteLine element       print column2 Console WriteLine  Column 2     foreach  var element in column2      Console WriteLine element     N B   Please note that this is just a very simple example  Using string Split does not account for cases where some records contain the separator   inside it  For a safer approach  consider using some csv specific libraries like CsvHelper on nuget

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I have been using csvreader com paid component  for years  and I have never had a problem   It is solid  small and fast  but you do have to pay for it   You can set the delimiter to whatever you like   using  CsvReader reader   new CsvReader s        reader Settings Delimiter            reader ReadHeaders        if headers on a line by themselves   Makes reader Headers   available     while  reader ReadRecord                use reader Values col i

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My favourite CSV parser is one built into  NET library  This is a hidden treasure inside Microsoft VisualBasic namespace  Below is a sample code   using Microsoft VisualBasic FileIO   var path     C  Person csv      Habeeb   Dubai Media City  Dubai  using  TextFieldParser csvParser   new TextFieldParser path      csvParser CommentTokens   new string             csvParser SetDelimiters new string              csvParser HasFieldsEnclosedInQuotes   true       Skip the row with the column names  csvParser ReadLine      while   csvParser EndOfData          Read current line fields  pointer moves to the next line    string   fields   csvParser ReadFields      string Name   fields 0     string Address   fields 1          Remember to add reference to Microsoft VisualBasic  More details about the parser is given here  http   codeskaters blogspot ae 2015 11 c-easiest-csv-parser-built-in-net html

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I have a library that is doing exactly you need   Some time ago I had wrote simple and fast enough library for work with CSV files  You can find it by the following link  https   github com ukushu DataExporter  It works with CSV like with 2 dimensions array  Exactly like you need   As example  in case of you need all of values of 3rd row only you need is to write   Csv csv   new Csv     csv FileOpen  c   file1 csv     var allValuesOf3rdRow   csv Rows 2     or to read 2nd cell of   var value   csv Rows 2  1

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You can do it like this   using System IO   static void Main string   args        using var reader   new StreamReader   C  test csv                  List lt string gt  listA   new List lt string gt             List lt string gt  listB   new List lt string gt             while   reader EndOfStream                        var line   reader ReadLine                var values   line Split                    listA Add values 0                listB Add values 1

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If you need to skip  head- lines and or columns  you can use this to create a 2-dimensional array       var lines   File ReadAllLines path  Select a   gt  a Split            var csv    from line in lines                               select  from col in line                select col  Skip 1  ToArray      skip the first column                 Skip 2  ToArray       skip 2 headlines   This is quite useful if you need to shape the data before you process it further  assuming the first 2 lines consist of the headline  and the first column is a row title - which you don t need to have in the array because you just want to regard the data    N B  You can easily get the headlines and the 1st column by using the following code       var coltitle    from line in lines                      select line Skip 1  ToArray      skip 1st column                      Skip 1  Take 1  FirstOrDefault   ToArray       take the 2nd row     var rowtitle    from line in lines select line 0     take 1st column                      Skip 2  ToArray       skip 2 headlines   This code example assumes the following structure of your   csv file     Note  If you need to skip empty rows - which can by handy sometimes  you can do so by inserting      where line Any a  gt  string IsNullOrWhiteSpace a     between the from and the select statement in the LINQ code examples above

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Still wrong   You need to compensate for    in quotes  Here is my solution Microsoft style csv                       lt summary gt          Microsoft style csv file     is the quote character     is an escaped quote           lt  summary gt           lt param name  fileName  gt  lt  param gt           lt param name  sepChar  gt  lt  param gt           lt param name  quoteChar  gt  lt  param gt           lt param name  escChar  gt  lt  param gt           lt returns gt  lt  returns gt      public static List lt string   gt  ReadCSVFileMSStyle string fileName  char sepChar        char quoteChar                      List lt string   gt  ret   new List lt string   gt              string   csvRows   System IO File ReadAllLines fileName            foreach  string csvRow in csvRows                        bool inQuotes   false              List lt string gt  fields   new List lt string gt                 string field                   for  int i   0  i  lt  csvRow Length  i                                  if  inQuotes                                           Is it a    inside quoted area   escaped litteral quote                      if i  lt  csvRow Length - 1  amp  amp  csvRow i     quoteChar  amp  amp  csvRow i 1     quoteChar                                                i                            field    quoteChar                                            else if csvRow i     quoteChar                                                inQuotes   false                                            else                                               field    csvRow i                                                           else    Not in quoted region                                        if  csvRow i     quoteChar                                                inQuotes   true                                            if  csvRow i     sepChar                                                fields Add field                           field                                                 else                                                field    csvRow i                                                                     if   string IsNullOrEmpty field                                 fields Add field                   field                                 ret Add fields ToArray                        return ret

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I have spend few hours searching for a right library  but finally I wrote my own code    You can read file  or database  with whatever tools you want and then apply the following routine to each line   private static string   SmartSplit string line  char separator              var inQuotes   false      var token           var lines   new List lt string gt         for  var i   0  i  lt  line Length  i              var ch   line i           if  inQuotes     process string in quotes                         if  ch                           if  i lt line Length-1  amp  amp  line i   1                                i                        token                                           else inQuotes   false                else token    ch            else               if  ch         inQuotes   true              else if  ch    separator                    lines Add token                   token                         else token    ch                          lines Add token       return lines ToArray

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The open-source Angara Table library allows to load CSV into typed columns  so you can get the arrays from the columns  Each column can be indexed both by name or index  See http   predictionmachines github io Angara Table saveload html   The library follows RFC4180 for CSV  it enables type inference and multiline strings   Example   using System Collections Immutable  using Angara Data  using Angara Data DelimitedFile        ReadSettings settings   new ReadSettings Delimiter Semicolon  false  true  null  null   Table table   Table Load  data csv   settings   ImmutableArray lt double gt  a   table  double-column-name   Rows AsReal   for int i   0  i  lt  a Length  i          Console WriteLine   0    1    i  a i        You can see a column type using the type Column  e g   Column c   table  double-column-name    Console WriteLine  Column  0  is double   1    c Name  c Rows IsRealColumn     Since the library is focused on F   you might need to add a reference to the FSharp Core 4 4 assembly  click  Add Reference  on the project and choose FSharp Core 4 4 under  Assemblies  -   Extensions

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I usually use this parser from codeproject  since there s a bunch of character escapes and similar that it handles for me

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Just came across this library  https   github com JoshClose CsvHelper  Very intuitive and easy to use  Has a nuget package too which made is quick to implement  http   nuget org packages CsvHelper 1 17 0  Also appears to be actively maintained which I like   Configuring it to use a semi-colon is easy  https   github com JoshClose CsvHelper wiki Custom-Configurations

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look at this  using CsvFramework   using System Collections Generic   namespace CvsParser    public class Customer       public int Id   get  set        public string Name   get  set        public List lt Order gt  Orders   get  set               public class Order       public int Id   get  set         public int CustomerId   get  set        public int Quantity   get  set         public int Amount   get  set         public List lt OrderItem gt  OrderItems   get  set        public class Address       public int Id   get  set        public int CustomerId   get  set         public string Name   get  set       public class OrderItem       public int Id   get  set        public int OrderId   get  set         public string ProductName   get  set       class Program       static void Main string   args                 var customerLines   System IO File ReadAllLines   Customers csv            var orderLines   System IO File ReadAllLines   Orders csv            var orderItemLines   System IO File ReadAllLines   OrderItemLines csv             CsvFactory Register lt Customer gt  builder   gt                        builder Add a   gt  a Id  Type typeof int   Index 0  IsKey true               builder Add a   gt  a Name  Type typeof string   Index 1               builder AddNavigation n   gt  n Orders  RelationKey lt Order  int gt  k   gt  k CustomerId               false       customerLines            CsvFactory Register lt Order gt  builder   gt                        builder Add a   gt  a Id  Type typeof int   Index 0  IsKey true               builder Add a   gt  a CustomerId  Type typeof int   Index 1               builder Add a   gt  a Quantity  Type typeof int   Index 2               builder Add a   gt  a Amount  Type typeof int   Index 3               builder AddNavigation n   gt  n OrderItems  RelationKey lt OrderItem  int gt  k   gt  k OrderId               true       orderLines             CsvFactory Register lt OrderItem gt  builder   gt                        builder Add a   gt  a Id  Type typeof int   Index 0  IsKey true               builder Add a   gt  a OrderId  Type typeof int   Index 1               builder Add a   gt  a ProductName  Type typeof string   Index 2                false       orderItemLines              var customers   CsvFactory Parse lt Customer gt

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LINQ way           var lines   File ReadAllLines  test txt   Select a   gt  a Split        var csv   from line in lines           select  from piece in line                   select piece       Wrong - Edit by Nick  It appears the original answerer was attempting to populate csv with a 2 dimensional array - an array containing arrays  Each item in the first array contains an array representing that line number with each item in the nested array containing the data for that specific column   var csv   from line in lines           select  line Split       ToArray

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Here is my variation of the top voted answer   var contents   File ReadAllText filename  Split   n    var csv   from line in contents           select line Split      ToArray      The csv variable can then be used as in the following example   int headerRows   5  foreach  var row in csv Skip headerRows       TakeWhile r   gt  r Length  gt  1  amp  amp  r Last   Trim   Length  gt  0         String zerothColumnValue   row 0      leftmost column     var firstColumnValue   row 1

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I am just student working on my master s thesis  but this is the way I solved it and it worked well for me  First you select your file from directory  only in csv format  and then you put the data into the lists   List lt float gt  t   new List lt float gt     List lt float gt  SensorI   new List lt float gt     List lt float gt  SensorII   new List lt float gt     List lt float gt  SensorIII   new List lt float gt     using  OpenFileDialog dialog   new OpenFileDialog          try               dialog Filter    csv files    csv    csv           dialog Multiselect   false          dialog InitialDirectory                dialog Title    Select file  only in csv format            if  dialog ShowDialog      DialogResult OK                        var fs   File ReadAllLines dialog FileName  Select a   gt  a Split                    int counter   0              foreach  var line in fs                                counter                    if  counter  gt  2        Skip first two headder lines                                       this t Add float Parse line 0                         this SensorI Add float Parse line 1                         this SensorII Add float Parse line 2                         this SensorIII Add float Parse line 3                                                         catch  Exception exc                MessageBox Show               Error while opening the file  n    exc Message               this Text               MessageBoxButtons OK               MessageBoxIcon Error

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Hi all  I created a static class for doing this    column check   quota sign removal  public static class CSV       public static List lt string   gt  Import string file  char csvDelimiter  bool ignoreHeadline  bool removeQuoteSign                return ReadCSVFile file  csvDelimiter  ignoreHeadline  removeQuoteSign              private static List lt string   gt  ReadCSVFile string filename  char csvDelimiter  bool ignoreHeadline  bool removeQuoteSign                string   result   new string 0           List lt string   gt  lst   new List lt string   gt              string line          int currentLineNumner   0          int columnCount   0              Read the file and display it line by line            using  System IO StreamReader file   new System IO StreamReader filename                         while   line   file ReadLine       null                                currentLineNumner                    string   strAr   line Split csvDelimiter                      save column count of dirst line                 if  currentLineNumner    1                                        columnCount   strAr Count                                      else                                         Check column count of every other lines                     if  strAr Count      columnCount                                                throw new Exception string Format  CSV Import Exception  Wrong column count in line  0    currentLineNumner                                                             if  removeQuoteSign  strAr   RemoveQouteSign strAr                    if  ignoreHeadline                                        if currentLineNumner   1  lst Add strAr                                     else                                       lst Add strAr                                                       return lst            private static string   RemoveQouteSign string   ar                for  int i   0 i lt  ar Count     i                          if  ar i  StartsWith          ar i  StartsWith       ar i    ar i  Substring 1               if  ar i  EndsWith          ar i  EndsWith       ar i    ar i  Substring 0 ar i  Length-1                      return ar

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Here s a special case where one of data field has semicolon       as part of it s data in that case most of answers above will fail   Solution it that case will be   string   csvRows   System IO File ReadAllLines FullyQaulifiedFileName   string   fields   null  List lt string gt  lstFields  string field  bool quoteStarted   false  foreach  string csvRow in csvRows        lstFields   new List lt string gt         field           for  int i   0  i  lt  csvRow Length  i                  string tmp   csvRow ElementAt i  ToString            if String Compare tmp        0                        quoteStarted    quoteStarted                    if  String Compare tmp          0  amp  amp   quoteStarted                        lstFields Add field               field                         else if  String Compare tmp           0                        field    tmp                      if  string IsNullOrEmpty field                 lstFields Add field           field                This will hold values for each column for current row under processing     fields   lstFields ToArray

[c#] Reading CSV file and storing values into an array

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