1 Estructura de Selección en Visual BasicCOMP 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 action1 Else action2 End If

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

5 ElseIf clauses If condition1 Then action1 ElseIf condition2 Then action2 ElseIf condition3 Then action3 Else action4 End If

6 Ejemplo programación ElseIfPublic Class Form1 Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click Dim gpa As Double Dim honors As String gpa = CDbl(TextBox1.Text) If gpa >= 3.9 Then honors = "summa cum laude..." ElseIf gpa >= 3.6 Then honors = "magna cum laude..." ElseIf gpa >= 3.3 Then honors = "cum laude..." ElseIf gpa >= 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 selector Case valueList action1 Case valueList action2 Case Else action of last resort End Select

8 Ejemplo programación Select CasePublic Class Form1 Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click Dim gpa As 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