Estructura de Selección en Visual Basic

1. Estructura de Selección en Visual Basic COMP 215

2. Definición • La estructura de selección la utilizamos cuando necesitamos programar el computador para que, dependiendo del cumplimiento o no de ciertas condiciones dentro del programa, se ejecuten o no instrucciones.

3. If Blocks • If condition Then action1Else action2End If

4. Flowchart general N Is the condition true? T Execute action2 Execute action1

5. ElseIf clauses If condition1 Then action1ElseIf condition2 Then action2ElseIf condition3 Then action3Else action4 End If

6. EjemploprogramaciónElseIf Public Class Form1 Private Sub Button1_Click(ByVal sender AsSystem.Object, ByVal e AsSystem.EventArgs) Handles Button1.Click DimgpaAs Double Dim honors As String gpa = CDbl(TextBox1.Text) If gpa >= 3.9 Then honors = "summa cum laude..." ElseIfgpa >= 3.6 Then honors = "magna cum laude..." ElseIfgpa >= 3.3 Then honors = "cum laude..." ElseIfgpa >= 2.0 Then honors = "........." Else honors = "You don't graduated..." End If TextBox2.Text = gpa & " " & honors End Sub End Class

7. Select Case Block Select Case selectorCasevalueList 1 action1CasevalueList 2 action2CaseElse action of last resortEnd Select

8. EjemploprogramaciónSelect Case Public Class Form1 Private Sub Button1_Click(ByVal sender AsSystem.Object, ByVal e AsSystem.EventArgs) Handles Button1.Click DimgpaAs Double Dim honors As String gpa = CDbl(TextBox1.Text) Select Case gpa Case Is >= 3.9 honors = "summa cum laude..." Case Is >=3.6 honors = "magna cum laude..." Case Is >= 3.3 honors = "cum laude..." Case Is >=2.0 honors = "........." Case Else honors = "You don't graduated..." End Select TextBox2.Text = gpa & " " & honors End Sub End Class