How to: Perform Basic String Manipulations in .NET

The following example constructs a class that performs string manipulations in a manner that might be found in a real-world application. The MailToData class stores the name and address of an individual in separate properties and provides a way to combine the City, State, and Zip fields into a single string for display to the user. Furthermore, the class allows the user to enter the city, state, and zip code information as a single string. The application automatically parses the single string and enters the proper information into the corresponding property.

For simplicity, this example uses a console application with a command-line interface.

Example

using System;

class MainClass
{
   static void Main()
   {
      MailToData MyData = new MailToData();

      Console.Write("Enter Your Name: ");
      MyData.Name = Console.ReadLine();
      Console.Write("Enter Your Address: ");
      MyData.Address = Console.ReadLine();
      Console.Write("Enter Your City, State, and ZIP Code separated by spaces: ");
      MyData.CityStateZip = Console.ReadLine();
      Console.WriteLine();

      if (MyData.Validated) {
         Console.WriteLine($"Name: {MyData.Name}");
         Console.WriteLine($"Address: {MyData.Address}");
         Console.WriteLine($"City: {MyData.City}");
         Console.WriteLine($"State: {MyData.State}");
         Console.WriteLine($"Zip: {MyData.Zip}");

         Console.WriteLine("\nThe following address will be used:");
         Console.WriteLine(MyData.Address);
         Console.WriteLine(MyData.CityStateZip);
      }
   }
}

public class MailToData
{
   string name = "";
   string address = "";
   string citystatezip = "";
   string city = "";
   string state = "";
   string zip = "";
   bool parseSucceeded = false;

   public string Name
   {
      get{return name;}
      set{name = value;}
   }

   public string Address
   {
      get{return address;}
      set{address = value;}
   }

   public string CityStateZip
   {
      get {
         return String.Format("{0}, {1} {2}", city, state, zip);
      }
      set {
         citystatezip = value.Trim();
         ParseCityStateZip();
      }
   }

   public string City
   {
      get{return city;}
      set{city = value;}
   }

   public string State
   {
      get{return state;}
      set{state = value;}
   }

   public string Zip
   {
      get{return zip;}
      set{zip = value;}
   }

   public bool Validated
   {
      get { return parseSucceeded; }
   }

   private void ParseCityStateZip()
   {
      string msg = "";
      const string msgEnd = "\nYou must enter spaces between city, state, and zip code.\n";

      // Throw a FormatException if the user did not enter the necessary spaces
      // between elements.
      try
      {
         // City may consist of multiple words, so we'll have to parse the
         // string from right to left starting with the zip code.
         int zipIndex = citystatezip.LastIndexOf(" ");
         if (zipIndex == -1) {
            msg = "\nCannot identify a zip code." + msgEnd;
            throw new FormatException(msg);
         }
         zip = citystatezip.Substring(zipIndex + 1);

         int stateIndex = citystatezip.LastIndexOf(" ", zipIndex - 1);
         if (stateIndex == -1) {
            msg = "\nCannot identify a state." + msgEnd;
            throw new FormatException(msg);
         }
         state = citystatezip.Substring(stateIndex + 1, zipIndex - stateIndex - 1);
         state = state.ToUpper();

         city = citystatezip.Substring(0, stateIndex);
         if (city.Length == 0) {
            msg = "\nCannot identify a city." + msgEnd;
            throw new FormatException(msg);
         }
         parseSucceeded = true;
      }
      catch (FormatException ex)
      {
         Console.WriteLine(ex.Message);
      }
   }

   private string ReturnCityStateZip()
    {
        // Make state uppercase.
        state = state.ToUpper();

        // Put the value of city, state, and zip together in the proper manner.
        string MyCityStateZip = String.Concat(city, ", ", state, " ", zip);

        return MyCityStateZip;
    }
}

Class MainClass
    Public Shared Sub Main()
        Dim MyData As New MailToData()

        Console.Write("Enter Your Name: ")
        MyData.Name = Console.ReadLine()
        Console.Write("Enter Your Address: ")
        MyData.Address = Console.ReadLine()
        Console.Write("Enter Your City, State, and ZIP Code separated by spaces: ")
        MyData.CityStateZip = Console.ReadLine()
        Console.WriteLine()

        If MyData.Validated Then
            Console.WriteLine("Name: {0}", MyData.Name)
            Console.WriteLine("Address: {0}", MyData.Address)
            Console.WriteLine("City: {0}", MyData.City)
            Console.WriteLine("State: {0}", MyData.State)
            Console.WriteLine("ZIP Code: {0}", MyData.Zip)

            Console.WriteLine("The following address will be used:")
            Console.WriteLine(MyData.Address)
            Console.WriteLine(MyData.CityStateZip)
        End If
    End Sub
End Class

Public Class MailToData
    Private strName As String = ""
    Private strAddress As String = ""
    Private strCityStateZip As String = ""
    Private strCity As String = ""
    Private strState As String = ""
    Private strZip As String = ""
    Private parseSucceeded As Boolean = False

    Public Property Name() As String
        Get
            Return strName
        End Get
        Set
            strName = value
        End Set
    End Property

    Public Property Address() As String
        Get
            Return strAddress
        End Get
        Set
            strAddress = value
        End Set
    End Property

    Public Property CityStateZip() As String
        Get
            Return String.Format("{0}, {1} {2}", strCity, strState, strZip)
        End Get
        Set
            strCityStateZip = value.Trim()
            ParseCityStateZip()
        End Set
    End Property

    Public Property City() As String
        Get
            Return strCity
        End Get
        Set
            strCity = value
        End Set
    End Property

    Public Property State() As String
        Get
            Return strState
        End Get
        Set
            strState = value
        End Set
    End Property

    Public Property Zip() As String
        Get
            Return strZip
        End Get
        Set
            strZip = value
        End Set
    End Property

    Public ReadOnly Property Validated As Boolean
        Get
            Return parseSucceeded
        End Get
    End Property

    Private Sub ParseCityStateZip()
        Dim msg As String = Nothing
        Const msgEnd As String = vbCrLf +
                                 "You must enter spaces between city, state, and zip code." +
                                 vbCrLf

        ' Throw a FormatException if the user did not enter the necessary spaces
        ' between elements. 
        Try
            ' City may consist of multiple words, so we'll have to parse the 
            ' string from right to left starting with the zip code.
            Dim zipIndex As Integer = strCityStateZip.LastIndexOf(" ")
            If zipIndex = -1 Then
                msg = vbCrLf + "Cannot identify a zip code." + msgEnd
                Throw New FormatException(msg)
            End If
            strZip = strCityStateZip.Substring(zipIndex + 1)

            Dim stateIndex As Integer = strCityStateZip.LastIndexOf(" ", zipIndex - 1)
            If stateIndex = -1 Then
                msg = vbCrLf + "Cannot identify a state." + msgEnd
                Throw New FormatException(msg)
            End If
            strState = strCityStateZip.Substring(stateIndex + 1, zipIndex - stateIndex - 1)
            strState = strState.ToUpper()

            strCity = strCityStateZip.Substring(0, stateIndex)
            If strCity.Length = 0 Then
                msg = vbCrLf + "Cannot identify a city." + msgEnd
                Throw New FormatException(msg)
            End If
            parseSucceeded = True
        Catch ex As FormatException
            Console.WriteLine(ex.Message)
        End Try
    End Sub
End Class

When the preceding code is executed, the user is asked to enter their name and address. The application places the information in the appropriate properties and displays the information back to the user, creating a single string that displays the city, state, and zip code information.