Use LINQ to read delimiter text files

Sometimes we process text files with delimiters. For example, data separated by commas (,), such:

Then they are stored in text files with the following columns:

• First Name
• Last Name
• Job Title
• City
• Country

   

  Before reading this file, create an object class:

     1:      /// <summary>

     2:      /// Customer entity

     3:      /// </summary>

     4:      /// Author Petter Liu http://wintersun.cnblogs.com

     5:      public class Customer

     6:      {

     7:          public string Firstname { get; set; }

     8:          public string Lastname { get; set; }

     9:          public string JobTitle { get; set; }

    10:          public string City { get; set; }

    11:          public string Country { get; set; }

    12:      }

  
  Next, we use LINQ to read the entire file:

     1:              var query = from line in File.ReadAllLines(filePath)

     2:                          let customerRecord = line.Split(,)

     3:                          select new Customer()

     4:                          {

     5:                              Firstname = customerRecord[0],

     6:                              Lastname = customerRecord[1],

     7:                              JobTitle = customerRecord[2],

     8:                              City = customerRecord[3],

     9:                              Country = customerRecord[4]

    10:                          };

    11:              foreach (var item in query)

    12:              {

    13:                  Console.WriteLine("{0}, {1}, {2}, {3}, {4}"

    14:                    , item.Firstname, item.Lastname, item.JobTitle, item.City, item.Country);

    15:              }

   

  To read a record that can contain conditions, we can filter out that Country is UK:

     1:              var query = from c in

     2:                              (from line in File.ReadAllLines(filePath)

     3:                               let customerRecord = line.Split(,)

     4:                               select new Customer()

     5:                               {

     6:                                   Firstname = customerRecord[0],

     7:                                   Lastname = customerRecord[1],

     8:                                   JobTitle = customerRecord[2],

     9:                                   City = customerRecord[3],

    10:                                   Country = customerRecord[4]

    11:                               })

    12:                          where c.Country == "UK"

    13:                          select c;

   

  Another example:

     1:              var query = from c in