如何：在 .NET 中執行基本字串操作
下列範例會使用基本字串作業主題中所討論的一些方法，以一種可能在實際應用程式中發現的方式，來建構可執行字串操作的類別。 MailToData 類別會將個人的姓名和地址儲存在不同的屬性中，並允許您將 City、State 和 Zip 欄位組合成單一字串，以便顯示給使用者看。 此外，類別可讓使用者以單一字串的形式輸入城市、省/市和郵遞區號資訊。 應用程式會自動剖析單一字串，並將適當的資訊輸入到對應的屬性。
為了簡單起見，這個範例會使用具有命令列介面的主控台應用程式。
範例
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
執行上述程式碼時，會要求使用者輸入自己的姓名和地址。 應用程式會將這項資訊放入適當的屬性中，並建立出顯示城市、省/市和郵遞區號資訊的單一字串，將資訊重新顯示給使用者看。
