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1、1Private Sub CmdCal_Click()Dim a As Integer, b As Integer, c As Integer, s As Single, area As Singlea = Val(Txta.Text)b = Val(Txtb.Text)c = Val(Txtc.Text)If a + b c And a + c b And c + b a Thens = (a + b + c) / 2area = Sqr(s * (s - a) * (s - b) * (s - c)Txtarea = CStr(area)ElseTxtarea = “输入数据无法构成三角形
2、三边“End IfCmdClear.SetFocus End Sub Private Sub CmdClear_Click()Txta.Text = “Txtb.Text = “Txtc.Text = “Txtarea.Text = “Txta.SetFocus End Sub Private Sub CmdEnd_Click()End End SubOption Explicit Private Sub CmdOld_Click()Dim y As Integer, m As Integer, d As Integer, birth As Datey = TxtYear2m = TxtMon
3、thd = TxtDaybirth = DateSerial(y, m, d) 调用系统函数 DateSerial 将年月日数据变成日期型数据返回TxtOld = (Date - birth) 365 & “岁“ End Sub Private Sub TxtDay_Change()If Val(TxtDay) 31 Or Val(TxtDay) 0 Or Val(TxtYear) Mod 100 = 0 And Val(TxtYear) Mod 400 29 ThenMsgBox “出生日输入错误！“ & vbCrLf & “请重新输入！“TxtDay.SelStart = 0TxtDay.
4、SelLength = Len(TxtDay)End IfElseIf Val(TxtDay) 28 ThenMsgBox “出生日输入错误！“ & vbCrLf & “请重新输入！“TxtDay.SelStart = 0TxtDay.SelLength = Len(TxtDay)End IfEnd IfEnd SelectEnd If End Sub Private Sub TxtDay_KeyPress(KeyAscii As Integer)If KeyAscii 12 Or Val(TxtMonth) 8 ThenIf KeyAscii 48 + 9 ThenMsgBox “出生月份输
5、入错误！“ & vbCrLf & “请重新输入！“KeyAscii = 0End IfEnd If End Sub Private Sub TxtYear_Change()If Val(TxtYear) Year(Date) ThenMsgBox “出生年份输入错误！“ & vbCrLf & “请重新输入！“TxtYear.SelStart = 0TxtYear.SelLength = Len(TxtYear)End If End Sub Private Sub TxtYear_KeyPress(KeyAscii As Integer)If KeyAscii = 0 Thenincome =
6、Val(TxtIncome)Select Case incomeCase Is = 5000tax = (income - 400) * 0.05Case Elsetax = (income - 400) * 0.04End SelectTxtTax = taxElse4MsgBox “收入输入错误！请重新输入！“TxtIncome = “TxtIncome.SetFocusEnd If End SubPrivate Sub CmbWeekDay_Click() 编写组合框 CmbWeekDay 的单击事件过程Select Case CmbWeekDay.TextCase “星期日“LblAr
7、rage.Caption = “休息“Case “星期一“, “星期三“LblArrage.Caption = “讲计算机课“Case “星期二“, “星期四“LblArrage.Caption = “讲程序设计课“Case “星期五“LblArrage.Caption = “进修英语“Case “星期六“LblArrage.Caption = “政治学习“End SelectLblArrage.Caption = CmbWeekDay.Text & “的工作安排是：“ & LblArrage.Caption End Sub Private Sub Form_Load()CmbWeekDay.
8、AddItem “星期日“CmbWeekDay.AddItem “星期一“CmbWeekDay.AddItem “星期二“CmbWeekDay.AddItem “星期三“CmbWeekDay.AddItem “星期四“CmbWeekDay.AddItem “星期五“CmbWeekDay.AddItem “星期六“ End Sub实验实验 6.1 已知小麦级别和数量，求小麦收购总价。 （设一级小麦的收购价是 1.3 元/公斤；二级小麦的收购价是 1.1 元/ 公斤；三级小麦的收购价是 0.9 元/公斤；）鼠标停留在三个级别上将提示各自的收购价。分析：首先在文本框中输入收购数量，然后选择级别，并根
9、据级别计算总价，公式为总价=单价*数量。5Private Sub cmdclear_Click()txtnum = “txttotal = “txtnum.SetFocus End Sub Private Sub cmdcal_Click()If OptL1.Value = True Thentxttotal = Str(Val(txtnum) * 1.3)ElseIf OptL2.Value = True Thentxttotal = Str(Val(txtnum) * 1.1)Elsetxttotal = Str(Val(txtnum) * 0.9)End If End Sub Priva
10、te Sub cmdexit_Click()End End Sub 实验实验 6.2 输入一串字符，限制字符串中只含有数字和字母，并将其中的字母和数字分开成为一个字母串和一个数字串。分析：在输入时即对每一个输入的字符进行判断（通常放在文本框的KeyPress事件中），符合条件的字符分类处 理，不符合条件的字符不予显示。Private Sub txtinput_KeyPress(KeyAscii As Integer)If KeyAscii = Asc(“0“) And KeyAscii = Asc(“a“) And KeyAscii = Asc(“A“) And KeyAscii ，欢迎你登录
11、！” ，否则显示“密码错误，请重新输入！ ” ； （3）输入 3 次错误密码后，显示“对不起，你没有权限！” ，退出程序。(a) 例6-3参考界面 (b) 帐号为空时的提示信息 (c)正确登录的信息(d)密码错误的提示信息 (e)三次密码错误后的提示分析： 对于登录问题在本章例 6-5 已有介绍，这里增加了输入错误次数的限制，使用全局变量存放输入错误密码的次数，当 次数超出时及时给出错误信息；在程序执行过程中，对用户输入时可能出现的错误进行了估计，并给出不同的错误提 示信息，这是编写代码前必须考虑的。 Dim N As Integer 全局变量 N Private Sub CmdExit_Cl
12、ick()If MsgBox(“确定退出登录么？“, vbOKCancel) = vbOK Then End End Sub Private Sub CmdLogin_Click()If txtname.Text = 3 Then MsgBox “对不起，你没有权限！对不起，你没有权限！“: End 错误次数达 3 次时MsgBox “密码错误，请重新输入！“, vbExclamationtxtpsw.Text = “txtpsw.SetFocusEnd IfElse 帐号为空时MsgBox “请输入帐号！请输入帐号！“, vbExclamationEnd If End Sub 实验实验 6.
13、4 判断是否是闰年。7分析：闰年的条件是：年份能被4整除，但不能被100整除；或能被400整除的整数Private Sub cmdtest_Click()Dim y As Integery = Val(txtyear.Text) If y Mod 4 = 0 And y Mod 100 trousers Thensuit = trousersclothes = clothes - suittrousers = 0Elsesuit = clothestrousers = trousers - suitclothes = 0End IfIf suit = 50 ThenTxtMoney = Cst
14、r(suit * 80 + clothes * 60 + trousers * 45)ElseTxtMoney = Cstr(suit * 90 + clothes * 60 + trousers * 45)End If End Sub 方法方法 2 Private Sub CmdCalMoney_Click()8Dim clothes As Integer, trousers As Integer, Money As Integerclothes 表示上衣数，trousers 表示裤子数clothes = Val(TxtClothes)trousers = Val(TxtTrousers)I
15、f clothes = trousers ThenIf clothes = 50 ThenMoney = clothes * 80ElseMoney = clothes * 90End IfElseIf clothes trousers ThenIf trous = 50 ThenMoney = trousers * 80 + (clothes - trousers) * 60ElseMoney = trousers * 90 + (clothes - trousers) * 60End IfElseIf clothes = 50 ThenMoney = clothes * 80 + (tro
16、users - clothes) * 45ElseMoney = clothes * 90 + (trousers - clothes) * 45End IfEnd IfEnd IfTxtMoney = Cstr(Money) End Sub 实验实验 6-6 随机生成简单的算式。分析： 简单算式中有三个部分需要产生：操作数 1、运算符、操作数 2，为了降低运算的难度，设定操作数 1 是在20，29的 整数，操作数 2 是在1，10的整数，运算符为“” 、 “” 、 “” 、 “” 。算式产生后，由用户输入结果， “判断结果” 按钮执行判断正误，且用户可以点击“重新出题”显示下一个随机算式。为了能执行判断，在产生算式时就应该将正 确
