Một số ví dụ ứng dụng visual basic 6 0

ð
ề
1 và 7:Tính lãi
suất…
Giao
diện:
Chương
trình:
Private Sub
cmdXacDinh_Click()
Dim SoTienCo As Single, LaiSuat As Single, SoTienCan As
Single,
SoNamCanGui As
Single
SoTienCo =
Text1
SoTienCan =
Text2
LaiSuat =
Text3
If SoTienCo >= SoTienCan
Then
Text4 =
"aaaa"
Else
Do
SoTienCo = SoTienCo * (1 + LaiSuat /
100)
SoNamCanGui = SoNamCanGui +
1
Loop While SoTienCo <=

SoTienCan
Text4 =
SoNamCanGui
Text5 =
SoTienCo
End
If
End
Sub
ð
ề
2 & 10:Lấy dữ liệu cổng com.Vẽ ñồ
thị
Giao
diện
Chương
trình:
Private Sub
cmdrun_Click()
Timer1.Enabled =
True
End
Sub
Private Sub
cmdStop_Click()
Timer1.Enabled =
False
End
Sub
Private Sub

Form_Load()
MSComm1.PortOpen =
True
End
Sub
Private Sub Form_Unload(Cancel As
Integer)
MSComm1.PortOpen =
False
End
Sub
Private Sub
Timer1_Timer()
Static x(), t(),
i
ReDim Preserve x(i) ' khai bao lai
mang
ReDim Preserve t(i) ' khai bao lai thoi
gian
If i = 0 Then Picture1.PSet (Picture1.Height, 0) ' khoi tao diem dau
con
tro
x(i) = MSComm1.Input ' doc gia tri vao tu cong
com1
Picture1.Line -(Picture1.Height - x(i) * 100, t(i) * 100) ' ve do
thi
i = i +
1
End
Sub

ð
ề3:Vẽ
y=(ax
2
+b)x.
ð
ưa
ra màn hình ñồ thị &ñiểm cực
tiểu
Giao
diện:Form1
Viết chương trình trong
Form2:
Private Sub
Form_GotFocus()
Dim x As Single, y As Double, GTCT As Double, GTCD As Double, y1
As
Double
Dim i As Integer, a As Single, b As
Single
'Form2.BackColor =
vbWhite
a =
Form1.Text1
b =
Form1.Text2
've he truc toa
do
Form2.Line (0, Form2.Height / 2)-(Form2.Width, Form2.Height /
2)

Form2.Line (Form2.Width / 2, 0)-(Form2.Width / 2,
Form2.Height)
'khac
so
For i = -3 To
3
CurrentX = (i + 3) * Form2.Width /
6
CurrentY = Form2.Height / 2 +
6
Print
i
Next
For i = -30 To 30 Step
2
CurrentX = Form2.Width / 2 -
6
CurrentY = (i + 30) * Form2.Height /
60
Print
i
Next
' ve do thi trong khoang -3 den 3 doi voi gia tri cua x va -30 den 30 doi
voi
gia tri cau
y
i =
0
For i = 0 To
500

x = -3 + i * 6 /
500
y = a * x ^ 3 + b *
x
Form2.Line -((x + 3) * Form2.Width / 6, Form2.Height - (y + 30)
*
Form2.Height /
60)
Next
'tinh cuc
tri
' y' = 3a*x^2 +
b
If a * b > 0 Or a = 0
Then
Form1.Text3 = "k0 ton
tai"
Form1.Text4 = "k0 ton
tai"
Else
x = b / (3 *
a)
GTCT = a * x ^ 3 + b *
x
x = -b / (3 *
a)
GTCD = a * x ^ 3 + b *
x
If GTCT > GTCD
Then

y1 =
GTCT
GTCT =
GTCD
GTCD =
y1
End
If
Form1.Text3 =
GTCT
Form1.Text4 =
GTCD
End
If
End
Sub
ð
ề
4:Nhân ma
trận
Giao
diện:
Private Sub
cmdcong_Click()
Dim i, j, mang1(4, 4) As Single, mang2(4, 4) As Single, mang3(4, 4)
As
Single
' nhap so lieu vao
mang
For i = 0 To

3
For j = 0 To
3
mang1(i, j) = Text1(i * 4 +
j)
mang2(i, j) = Text2(i * 4 +
j)
Next
Next
' thuc hien phep
cong
For i = 0 To
3
For j = 0 To
3
mang3(i, j) = mang1(i, j) + mang2(i,
j)
Next
Next
'dua ket qua ra man
hinh
For i = 0 To
3
For j = 0 To
3
Text3(i * 4 + j) = mang3(i,
j)
Next
Next
End

Sub
Private Sub
cmdnhan_Click()
Dim i, j, mang1(4, 4) As Single, mang2(4, 4) As Single, mang3(4, 4)
As
Single
Dim
k
' nhap so lieu vao
mang
For i = 0 To
3
For j = 0 To
3
mang1(i, j) = Text1(i * 4 +
j)
mang2(i, j) = Text2(i * 4 +
j)
Next
Next
' thuc hien phap
nhan
For i = 0 To
3
For j = 0 To
3
For k = 0 To
3
mang3(i, j) = mang3(i, j) + mang1(i, k) * mang2(k,
j)

Next
Next
Next
'dua ket qua ra man
hinh
For i = 0 To
3
For j = 0 To
3
Text3(i * 4 + j) = mang3(i,
j)
Next
Next
End
Sub
ð
ề
5:Nhập và phát xung RTS &
DTR
Dim xung_rts As Integer, xung_dtr As
Integer
Private Sub
cmdphat_Click()
Timer1.Interval = Round(1000 / (2 * Text3)) ' dinh thoi gian timer1
tuong
ung voi tan
so
Timer1.Enabled = True ' cho phep timer1 hoat
dong
xung_rts =

Text1
xung_dtr =
Text2
End
Sub
Private Sub
Form_Load()
MSComm1.PortOpen =
True
End
Sub
Private Sub Form_Unload(Cancel As
Integer)
MSComm1.PortOpen =
False
End
Sub
Private Sub
Timer1_Timer()
Static x As Boolean, y As
Boolean
' phat xung ra chan
RTS
If xung_rts > 0
Then
If x = False
Then
MSComm1.RTSEnable = False ' RTS =
0
x =

True
Else
MSComm1.RTSEnable = True ' RTS =
1
x =
False
xung_rts = xung_rts -
1
Text4 =
xung_rts
End
If
End
If
' phat xung ra chan
DTR
If xung_dtr > 0
Then
If y = False
Then
MSComm1.DTREnable = False ' DTR =
0
y =
True
Else
MSComm1.DTREnable = True ' DTR =
1
y =
False
xung_dtr = xung_dtr -

1
Text5 =
xung_dtr
End
If
End
If
' dung timer1 khi da phat het
xung
If (xung_rts = 0) And (xung_dtr = 0)
Then
Timer1.Enabled = False ' dung
timer1
MsgBox "da phat xong" ' bao da phat
xong
End
If
End
Sub
ð
ề
6:Viết chương trình ñèn giao
thông
Private Sub
cmdrun_Click()
Timer1.Enabled =
True
End
Sub
Private Sub

cmdstop_Click()
Timer1.Enabled =
False
' tat cac
den
For j = 0 To
11
Label1(j).BackColor =
vbBlack
Next
End
Sub
Private Sub
Form_Load()
Dim
i
For i = 0 To
11
Label1(i).BackColor =
vbBlack
Next
i
End
Sub
Private Sub
Timer1_Timer()
Dim x As Integer, v As Integer, d As
Integer
Dim
j

Static
t
x =
Text1
v =
Text2
d = x +
v
' thuat giai (tinh theo 1 chu ky thoi
gian)
' x v d duong
1
' d x v duong
2
For j = 0 To
11
Label1(j).BackColor =
vbBlack
Next
' chon cho duong
1
Select Case
t
Case Is <= x: Label1(0).BackColor = vbGreen '
xanh
Label1(6).BackColor =
vbGreen
Case Is <= x + v: Label1(1).BackColor = vbYellow '
vang
Label1(7).BackColor =

vbYellow
Case Is <= 2 * (x + v): Label1(2).BackColor = vbRed '
do
Label1(8).BackColor =
vbRed
End
Select
'chon cho duong
2
Select Case
t
Case Is <= d: Label1(5).BackColor = vbRed '
do
Label1(11).BackColor =
vbRed
Case Is <= d + x: Label1(3).BackColor = vbGreen '
xanh
Label1(9).BackColor =
vbGreen
Case Is <= 2 * (x + v): Label1(4).BackColor = vbYellow '
vang
Label1(10).BackColor =
vbYellow
End
Select
t = t +
1
If t > 2 * d Then t =
0
'##### doan nay dung de tao ra "dong ho" => k0 can phai them

vao
Label3 =
Time
'##################################3
End
Sub
ð
ề
8:Vẽ ñồ thị
y=ax(bx+c)
Private Sub
Form_GotFocus()
Dim x As Single, y As Double, GTCT As Double, GTCD As Double, y1
As
Double
Dim i As Integer, a As Single, b As
Single
'Form2.BackColor =
vbWhite
a =
Form1.Text1
b =
Form1.Text2
've he truc toa
do
Form2.Line (0, Form2.Height / 2)-(Form2.Width, Form2.Height /
2)
Form2.Line (Form2.Width / 2, 0)-(Form2.Width / 2,
Form2.Height)
'khac

so
For i = -3 To
3
CurrentX = (i + 3) * Form2.Width /
6
CurrentY = Form2.Height / 2 +
6
Print
i
Next
For i = -30 To 30 Step
2
CurrentX = Form2.Width / 2 -
6
CurrentY = (i + 30) * Form2.Height /
60
Print
i
Next
' ve do thi trong khoang -3 den 3 doi voi gia tri cua x va -30 den 30 doi
voi
gia tri cau
y
i =
0
For i = 0 To
500
x = -3 + i * 6 /
500
y = a * b * x ^ 2 + a *

x
Form2.Line -((x + 3) * Form2.Width / 6, Form2.Height - (y + 30)
*
Form2.Height /
60)
Next
'tinh cuc
tri
' y' = 2abx +
a
If a * b = 0
Then
Form1.Text3 = "k0 ton
tai"
Else
x = -1 / (2 *
b)
y = a * b * x ^ 2 + a *
x
Form1.Text3 =
y
End
If
End
Sub