C# 选择语句（开发者如何使用）

// Switch statement
switch (variable)
{
    case value1:
        // Code to execute if variable equals value1
        break;
    case value2:
        // Code to execute if variable equals value2
        break;
    // More cases as needed
    default:
        // Code to execute if variable doesn't match any case
        break;
}

' Switch statement
Select Case variable
	Case value1
		' Code to execute if variable equals value1
	Case value2
		' Code to execute if variable equals value2
	' More cases as needed
	Case Else
		' Code to execute if variable doesn't match any case
End Select

int number = 3;
switch (number)
{
    case 1:
        Console.WriteLine("One");
        break;
    case 2:
        Console.WriteLine("Two");
        break;
    case 3:
        Console.WriteLine("Three");
        break;
    default:
        Console.WriteLine("Other Number"); // Print to console
        break;
}

Dim number As Integer = 3
Select Case number
	Case 1
		Console.WriteLine("One")
	Case 2
		Console.WriteLine("Two")
	Case 3
		Console.WriteLine("Three")
	Case Else
		Console.WriteLine("Other Number") ' Print to console
End Select

default:
    // Code to execute if no case matches
    break;

Case Else
	' Code to execute if no case matches
	break

int day = 5;
string dayName;
switch (day)
{
    case 1:
        dayName = "Monday";
        break;
    case 2:
        dayName = "Tuesday";
        break;
    case 3:
        dayName = "Wednesday";
        break;
    case 4:
        dayName = "Thursday";
        break;
    case 5:
        dayName = "Friday";
        break;
    case 6:
        dayName = "Saturday";
        break;
    case 7:
        dayName = "Sunday";
        break;
    default:
        dayName = "Invalid day";
        break;
}
Console.WriteLine(dayName);

Dim day As Integer = 5
Dim dayName As String
Select Case day
	Case 1
		dayName = "Monday"
	Case 2
		dayName = "Tuesday"
	Case 3
		dayName = "Wednesday"
	Case 4
		dayName = "Thursday"
	Case 5
		dayName = "Friday"
	Case 6
		dayName = "Saturday"
	Case 7
		dayName = "Sunday"
	Case Else
		dayName = "Invalid day"
End Select
Console.WriteLine(dayName)

var result = variable switch
{
    value1 => result1,
    value2 => result2,
    _ => defaultResult
};

'INSTANT VB TODO TASK: The following 'switch expression' was not converted by Instant VB:
'var result = variable switch
'{
'	value1 => result1,
'	value2 => result2,
'	_ => defaultResult
'};

int temperature = 25;
string weatherDescription = temperature switch
{
    <= 0 => "Freezing",
    < 20 => "Cold",
    < 30 => "Mild",
    _ => "Hot"
};
Console.WriteLine(weatherDescription);

Dim temperature As Integer = 25
'INSTANT VB TODO TASK: The following 'switch expression' was not converted by Instant VB:
'string weatherDescription = temperature switch
'{
'	<= 0 => "Freezing",
'	< 20 => "Cold",
'	< 30 => "Mild",
'	_ => "Hot"
'};
Console.WriteLine(weatherDescription)

object obj = // some object;
string description = obj switch
{
    int i => $"Integer: {i}",
    string s => $"String: {s}",
    _ => "Unknown type"
};

'INSTANT VB TODO TASK: The following 'switch expression' was not converted by Instant VB:
'object obj = string description = obj switch
'{
'	int i => $"Integer: {i}",
'	string s => $"String: {s}",
'	_ => "Unknown type"
'};

using IronPdf;

class Program
{
    static void Main(string[] args)
    {
        IronPdf.License.LicenseKey = "Your-License-Code";
        PdfDocument pdf = PdfDocument.FromFile("sample.pdf");
        // Define different watermark HTML for each case
        string watermarkHtmlOnePage = "<div style='color:red;'>One Page Document</div>";
        string watermarkHtmlTwoPage = "<div style='color:blue;'>Two Page Document</div>";
        switch (pdf.PageCount)
        {
            case 1:
                // Apply watermark for one-page document
                pdf.ApplyWatermark(watermarkHtmlOnePage);
                break;
            case 2:
                // Apply watermark for two-page documents
                pdf.ApplyWatermark(watermarkHtmlTwoPage);
                break;
            default:
                // Apply a default watermark for other cases
                pdf.ApplyWatermark("<div style='color:green;'>Multiple Page Document</div>");
                break;
        }
        // Save the watermarked PDF
        pdf.SaveAs("watermarked.pdf");
    }
}

Imports IronPdf

Friend Class Program
	Shared Sub Main(ByVal args() As String)
		IronPdf.License.LicenseKey = "Your-License-Code"
		Dim pdf As PdfDocument = PdfDocument.FromFile("sample.pdf")
		' Define different watermark HTML for each case
		Dim watermarkHtmlOnePage As String = "<div style='color:red;'>One Page Document</div>"
		Dim watermarkHtmlTwoPage As String = "<div style='color:blue;'>Two Page Document</div>"
		Select Case pdf.PageCount
			Case 1
				' Apply watermark for one-page document
				pdf.ApplyWatermark(watermarkHtmlOnePage)
			Case 2
				' Apply watermark for two-page documents
				pdf.ApplyWatermark(watermarkHtmlTwoPage)
			Case Else
				' Apply a default watermark for other cases
				pdf.ApplyWatermark("<div style='color:green;'>Multiple Page Document</div>")
		End Select
		' Save the watermarked PDF
		pdf.SaveAs("watermarked.pdf")
	End Sub
End Class