?2? VB.NET????

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?2? VB.NET????
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• 2.1 ??????
• 2.2 ??????????
• 2.3 ???????
• 2.4 ??????
• 2.5 ??????
• 2.6 ???????

????
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2.1.1 ??????
2.1 ??????
?????????????,???????????????????????
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• Public Class Form1
• Private Sub Button1_Click( ByVal sender As
  System.Object, ByVal e As _
• 
  System.EventArgs) Handles Button1.Click
• Dim a, b, c, maxside As Single
• Dim perimeter, area As Double
• a Val(TextBox1.Text)
• b Val(TextBox2.Text)
• c Val(TextBox3.Text)
• If a b gt c And b c gt a And a c gt b
  Then '??????
• perimeter a b c
• Dim p As Double perimeter / 2
• area Math.Sqrt(p (p - a) (p -
  b) (p - c))
• maxside Math.Max(a, Math.Max(b, c))
• Label2.Text "???????" a "?"
  b "?" c vbCrLf
• Label2.Text "???????"
  Format(perimeter, "0.00") vbCrLf
• Label2.Text "???????"
  Math.Round(area, 4) vbCrLf
• Label2.Text "????????" maxside
  vbCrLf
• Else

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2.2 ??????????
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2.2.1 ???????

• ????????????????
• ?????????????????????
• ??????

(1)????????,????????????????
???????????,????? (2) ????VB.NET????????Dim?If?For
?? (3)????????????????,????????? (4)?????????????,
XYZ,xyz,xYz??????????????????????,????????????,???
??????????????????
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2.2.2 ????
???????????????? ??????????????
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????????
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1. ???

• ????Integer(??Short ?Long)
• ?? n
• ??123?-123?123?123i?????
• 123.0?1,234?????
• ????Single (??Double )
• ?? n.n?nEm?n.nEm
• ??123.45?0.12345E3 (0.12345103 )

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• (1)??
• ???????????????
• ???????,???????
• ????n
• ? 123?123?123 ?????
• 123.0 ?1,230 ??
• ???? On
• ?????Hn

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• (2)??
• ??????????????
• ?????????,??????
• ????? Single?!, ???Double? ?
• ?? ?? E ??
• ?? E ??
• ?? E????????? ?????????
• ? 123.45? 123.45?0.12345E3?
• 12345E-2 ? 0.12345E3 ?? ????

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2. ???

• ???(Char)????Unicode??
• ?????????????,?????.
• ?? "??"
• ?? " a"?" 2"?"?"??
• ???(String)?????????
• ?? "???"
• ??,"12345"?"abcde123"?"????"??

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• ??
• (1)???????????????????
• (2)""?????,?" "??????????
• (3) ?????????,??,??????123"abc,???????????,?
  "123""abc"?

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??????????????

• 3xy ' ????
• y - z ' ??????????
• Wang Ping ' ???????
• Dim ' VB.NET????
• Cos ????????,? ???,??????

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3. ????

• ?????(Boolean)
• ??????????
• ?(True)??(False)
• ??
• ????????????????,0 ???False,?0????True?
• ????????????????, False???0,True???-1?

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• ?????(Date)
• ?? ????/?/?

? 3-6-93 1320 12/18/1999
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2.2.3 ??

• VB.NET??????
• ???? ????????????
• ???? ????,?????????
• Const ????? As ?? ???
• ? Const PI3.14
• ???? ?????????????
• ??vbCrLf ??/?????
• ?? ????????????
• ?????.???
• ? Color.Red

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2.2.4 ??
1.????? ???????????????????? ?????????
???? ??????? ????? ???????????? ????
????????????
VB.NET????????,????????
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1. Dim??
???????????,??????? ???? Dim ??? As
????? As???? ??????Object?? ????? ??????????
????Dim??????????? ????????,????As???,
?????,??????????? ??Dim m,n,j As Integer,x,y As
Single,k
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2. Static??
?Static?????????? ??????????????.
????Static ??? AS ??
??Dim?Static??????
Sub Form_Click() Dim Count CountCount 1
Label1.Text "?????" _ Count "?" End Sub
Sub Form_Click() Static Count CountCount
1 Label1.Text "?????" _ Count "?" End
Sub
?Dim?????,????????????
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2.2.5 ??????
????????,???????,?????????

• ??? ?????????,????????.
• ????? ???????Dim?Static???????,?????????
• ????? ???????????Dim?Private????,????????????
• ???? ?????Public????,????????????????

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??????
?????????????????????? Public Pa As integer
' ???? Private Mb As string 10 '
??/????? Sub F1( ) Dim Fa As
integer ????? End Sub Sub F2(
) Dim Fb As Single ????? For i1
to 10 Dim k ???
Next i End Sub
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2.3 ???????
??????? ???? ???????????
?? ????????????? ???
??????????? ?? ???????????
??
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1. ?????
???????????????????,??????????,??????????????? ??
30-True ???31,???True????-1,False????0 False
10 "4" ???14
?510 mod 10 \ 9 / 32 2 ??10
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• ? ?????????????,?????,??????????

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2.????????
?????????,?????????? ????????????
1)??????????? 2)???????,??????,???????? ?????
????? 3)????????,???????,????? ??
?? ?? ?? "ab"
123 "ab123 " "ab" 12 ?? "12"
456 " 12456 " "12" 456 468 "12"
True "12True" "12" True 11 ??
??????????,??????????
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• ?????????????,?????????????,???????

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• Public Class Form1
• Private Sub Button1_Click(ByVal sender As
  System.Object, _
• ByVal e As System.EventArgs)
  Handles Button1.Click
• Dim a, b As Double
• a TextBox1.Text
• b TextBox2.Text
• TextBox3.Text a b
• End Sub
• Private Sub Button2_Click(ByVal sender As
  System.Object, _
• ByVal e As System.EventArgs)
  Handles Button2.Click
• TextBox4.Text TextBox1.Text
  TextBox2.Text
• End Sub
• End Class

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3.?????
???????????????, ???True?False?
??? ? ??
" ABCDE " " ABR " False
gt " ABCDE " gt " ABR " False
gt " bc" gt "abcde " True
lt 23lt3 False
lt " 23 " lt " 3 " True
ltgt " abc" ltgt "abcde " True
Like "ABCDEFG" Like "DE" True
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4.?????
??????Not???????,?????????,?????????????,??????Tru
e?False?
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? ?????60xlt70?VB.NET??????
????????,????????? ??(Age)??19?,?????(Total)??
285?, ??????100?,???????? Agelt19 And Totalgt285
And ( Mark1100 Or Mark2100 Or Mark3100
) ???????????
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2.3.2???

• 1.?? ????????????????
• 2.????
• ??????? ?a -b????
• ?????? ?x ??y ???xy
• ????????(??????)
• ???????????????,??????
• 3 ???
• ?????gt?????gt?????gt????

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???????
abcd/e/f/g ? abcd/(efg)
sin(453.14/180)(exp(10)log(10))/sqr(xy1)
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2.3.3 ????
?? ?????? ???. ??????
?????????,?????????????? ???????????VB??????????
. ?? x!0.1 ' x??????,??0.1 TextBo
x1.Text "" ' ???????? TextBox1.Text
"????VB.Net "
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??????
???????,?????????,??????????????? ???
??????? ??? ???????????,???????????????,????????
????????- ??\?/??
??a b4 ??? a a(b4)
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????????

• ?? sum x ??? sum sumx
• ?? n 1 ??? n n1
• ?????? ?? ???

????,TextBox1????? TextBox1.Text " VB.NET "
vbCrLf TextBox1.Text "??????"
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2.3.4 ???????????

• 1. ??????
• ??????????????
• ???????????????????
• IntegerltLongltSingleltDoubleltCurrency
• 2. ??????
• ??????????

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2.4 ???????
2.4.1 InputBox?? ???????,??????,???????????? ??
InputBox(??,??,???,x????,y????)
?????????? ??????,???? ???????vbCrLf?
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2.4.2 MsgBox??
???????,???????????? MsgBox??????????, ??
MsgBox(??,??,??) MsgBox????????
MsgBox ??,??,??
????????????????(??)? ???????????? ?????????????
?,??????MsgBoxStyle ?MsgBoxResult
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MsgBox????
?? MsgBoxStyle
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(No Transcript)
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MsgBox???????
??? MsgBoxResult
?4.3 ??????????????,??????,?????????,??????,??????
,????
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? ????????????????,????????????????????,??
?????????????????
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• Private Sub Form1_FormClosing(.)Handles
  Me.FormClosing
• Dim result As Integer
• result MsgBox("??????", _
• 
  MsgBoxStyle.OkCancel _
• 
  MsgBoxStyle.Critical, "??????")
• If result MsgBoxResult.Ok Then
• MsgBox("?????!") '????????
• Else
• e.Cancel True '????
• End If
• End Sub

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2.4.3 Format??????

• ?????
• Format(???,,??)

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2.4.4 Debug.write??

• ??????????Write???????WriteLine??????????
• Debug. WriteLine(???)
• Debug. Write (???)
• ? ??????
• Debug.WriteLine("??????" x " ?????"
  jbgz)
• Debug.Write("???????" sfgz)
• ????????????????

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2.5.1.????
2.5 ??????
. NET?????????Math?????????????? Imports
System.Math??
? ??Windows???.
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???????

• ? ???? ???????,????? ? ????,?????????????.
• ? ???? ?????????
• ? ??Math?????sqrt
• Label1.Text system.Math.sqrt(100)
• ? Imports???? ??
• Imports ????
• ?? ?Public Class Form1??

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?? ? ? ? ? ? ?
Abs(N) ?N???? Abs(-3.5) 3.5
Cos(N) ??N?????? Cos(0) 1
Exp(N) ???e????,?eN Exp(3) 20.086
Pow(N1,N2) ???N1??,N2??? Pow(-5,2) 25
Log(N) ?????? Log(10) 2.3
Max(N1,N2) ?????????? Max(3,5) 5
Min(N1,N2) ?????????? Min(3,5) 3
Sin(N) ??N?????? Sin(0) 0
Sign(N) ??N????? Sign(-3.5) -1
Sqrt(N) ?N???? Sqrt(9) 3
Tan(N) ??N????? Tan(0) 0
Round?Ceiling?Floor
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2.5.2.????
Int?Fix?IsNumeric
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??????

• Chr?Asc????????Chr(Asc(r))
• Chr(66) ? B Asc (B") ? 66
• Asc(Chr(66)) ? 99 Chr(Asc(K)) ? K
• Ucase("abcdefg") ? ABCDEFG"
• (2) Str???????????????,?????????????????
• (3) Val?????????????,????????????????????,?????,??
  ??????????????????
• Val("-123.45ty3")???-123.45?

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2.5.3. ?????
????? VB.NET?????????(?????)???,?????????????????,
??????????VB.NET??Unicode?????????? VB.NET????????
??? ? ??????VB6.0??????? ?
?????System.String????(??)
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??? ?? ?? ??
Len(s) ?s???????? Len("ab??") 4
Left(s,n) ?s??????n??? Microsoft.VisualBasic .Left("ABcde",2) "AB"
Right(s,n) ?s??????n??? Microsoft.VisualBasic .Right("ABcde",2) "de"
Mid(s,b,n) ?s??????b????????n???,??????????n,??????????????? Mid("ABcde",2,3) "Bcd"
LTrim(s) ??s????? LTrim("  ABC  ") "ABC  "
RTrim(s) ??s????? RTrim("  ABC  ") "  ABC"
Trim(s) ??s????? Trim("  ABC  ")  "ABC"
Instr(s1,s2) ??s2?s1?????????,?????????,??0 Instr("WBAC","B") 2
StrDup(n,c) ???n??????????? StrDup (3,"a") "aaa"
Space (n) ??n??? Space (3) "???"
Replace(s,s1,s2) ????s??s2??s1 Replace("ABCASA","A","8") "8BC8S8"
StrReverse (s) ?????? StrReverse ("abcd") "dcba"
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????????
StrDup(5,A)
???"AAAAA" InStr("EFABCDEFG","EF")
???1 Trim("???ABC???") ???"ABC" Left("ABCDE"
,2) ???"AB" Right("ABCDE",2)
???"DE" Mid("ABCDE",2,3)
???"BCD" Mid("ABCDE",2,6)
???"BCDE"
?? ??Right?Left??????????????
Microsoft.VisualBasic,?????????Right?Left???
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• ?????????????????????????????????ABCD??????,
  ????????,??????????

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2.5.4.???????
Now ????????? WeekDay ??????
DateAdd(???????,???,????????)
DateDiff(???????,??1,??2) ???????????????(??2012?
6?30 ?)?????????? DateDiff("d", Now,
6/30/2012) ???? year month day hour
Minute
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• ?????

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2.5.5 ????

• Rnd????
• ????
• Rnd()?Rnd(N)
• ?? ??0,1)???????
• Ngt0????,?????,
• N0????????????

?????????,??????? Int(Rnd(??-??1)??)
???1100 ?Int(Rnd1001)
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• ??
• ????,???????????
• ???????????,????? Randomize

? ????10?????
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2.5.6. Shell??
Shell???????????? ???? Shell(?????,????) ?????
??????????(????) ????????,04,6,1?????? ??
Shell(c\windows\system32\calc.exe,1)
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2.6 ???????

• ??????????,????????????
• ????,??????????,?????????,????????
• ?????,?????????????????,????????,????????????????
• VB??????????????????????

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2.6.1 ????
?????????????????? 1.????
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2.????
??????????????????,???????????????????????????,???
????????
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3.????

?????,?????????,??????????????,???????????????????
???????????????,??????????????,???????,???????????
???,???????????
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2.6.2 ????
VB.NET????? (1) ????(??) ???????????????????????
(2) ????(??) ?????????????????,????????,?????? (3
) ????(Break) ??????,?????????????????????????????
?
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?????-????

??????????