Conf. dr. Cozgarea Adrian
Structuri de control in VB.NET
1. Structura liniara
2. Structura alternativa
3. Structura repetitiva
Structura liniara
Exemplu:
Dim fact as Factura=New Factura()
fact.Numar=101
fact.Data=Now()
fact.Valoare=1000
fact.CotaTVA=0.24
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Structuri alternative
IF
SELECT CASE
TRY
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IFTHENELSE
1. Sintaxa general:
If conditie1 [ Then ]
[instructiuni1]
[ ElseIf conditie2 [ Then ]
[instructiuni2] ]
[ Else
[ instructiuni3] ]
End If
2. Sintaxa restrns:
If conditie Then [ instructiune1 ] [ Else [ instructiune2 ] ]
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Exemplu IF
If CType(txtNota.Text, Integer)
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SELECT CASE ... END SELECT
Select [ Case ] expresie
[ Case listExpresii1
[ Instruciuni ] ]
[ Case listExpresii2
[ Instruciuni 2] ]
[ Case Else
[ InstruciuniN ] ]
End Select
, unde listExpresii1, listExpresii2:- expresie1 To expresie2
- [ Is ] operatorComparare expresie
- expresie
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Exemplu SELECT CASE
Dim tipCont As String = InputBox("Tastati tip cont: ")
Select Case tipCont.ToUpper()
Case "A"
MsgBox("Cont de activ")
Case "P"
MsgBox("Cont de pasiv")
Case "B"
MsgBox("Cont bifunctional")
Case Else
MsgBox(Cont eronat !")
End Select
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Structuri repetitive
While
Do
For
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WHILE ... END WHILE
While conditie
[ Instruciuni1 ]
[ Exit While ]
[ Instruciuni2 ]
End While
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Exemplu While
Dim i As Integer=1
While i
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Do Loop
Condiionare anterioar:
Do { While | Until } conditie
[ instructiuni1 ]
[ Exit Do ]
[ instructiuni2 ]
Loop
Condiionare posterioar:
Do
[ instructiuni1 ]
[ Exit Do ]
[ instructiuni2 ]
Loop { While | Until } conditie
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Exemple DoLoop
Condiionare anterioar
Dim x As Integer=1
Do While x
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ForNext
Sintaxa 1:
For contor [As tipData]=start To final [Step pas]
[ instructiuni1 ]
[ Exit For ]
[ instructiuni2 ]
Next [ contor ]
Sintaxa 2 (pentru parcurgerea unei multimi):
For Each element [ As tipData ] In multime
[ instructiuni1 ]
[ Exit For ]
[ instructiuni2 ]
Next [ element ]
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Exemple ForNext
Dim x as Integer
For x=0 To 2
MsgBox (x)
Next ' aici este incrementat contorul x
MsgBox (x) ' afiseaza 3 (iteraii)
Dim x As Double=0
For i As Integer=0 To 100 Step 2 ' parcurge numerele pare pe interv. [0,100]
x=x+i
Next
MsgBox (x)
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