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c#中combox控件，如果没选，为空，就MessageBox.Show提示不能为空，具体要怎么写
没必要套嵌elseprivate void btnlanding_Click(object sender, EventArgs e) { string result=cbotype.selectedtext.tostring(); if (txtuser.Text == "") { MessageBox.Show("用户名不能为空", "输入提示", MessageBoxButtons.OKCancel, MessageBoxIcon.Asterisk); } if (tetpwd.Text == "") { MessageBox.Show("密码不能为空", "输入提示", MessageBoxButtons.OKCancel, MessageBoxIcon.Exclamation); } if(result.length《=0) ///不能获取combox中的值 { MessageBox.Show("类型不能为空", "选择提示", MessageBoxButtons.OKCancel, MessageBoxIcon.Hand); } }
C#中combox控件选中下拉列表问题
comboBox1.DataSource=DataTable1;//comboBox1为comboBox控件名，DataTable1为内存表，为DataTable的一个实例comboBox1.DisplayMember="数据表字段名";comboBox1.ValueMember="数据表字段名";//最好写在窗体的Load事件里面
如何使用VB中的COMBOX控件
假设程序运行后单击combo1里的名字，datagrid对应显示记录代码如下：Private Sub Form_Load()Adodc1.ConnectionString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=F:\VB\1-数据库相关\adodc\01.mdb;Persist Security Info=False"Adodc1.CommandType = adCmdTextAdodc1.RecordSource = "select * from 成绩单"Set DataGrid1.DataSource = Adodc1Set Combo1.DataSource = Adodc1For i = 1 To Adodc1.Recordset.RecordCountCombo1.AddItem Adodc1.Recordset("姓名").ValueAdodc1.Recordset.MoveNextNext iEnd Sub Private Sub Combo1_click()Adodc1.RecordSource = "select * from 成绩单 where 姓名=’" & Combo1.Text & "’"Adodc1.RefreshEnd Sub 把我代码中的路径和字段名改成你的即可
vb 中combox控件的使用
’添加窗体Form1,按钮Command1,Command2,Command3,组合框Combo1,然后添加如下代码:Private Sub Form_Load() Combo1.AddItem "1" Combo1.AddItem "2" Combo1.AddItem "3" Command1.Visible = False Command2.Visible = False Command3.Visible = FalseEnd SubPrivate Sub Combo1_Click() Command1.Visible = False Command2.Visible = False Command3.Visible = False If Combo1.Text = "1" Then Call setButton(Command1) ElseIf Combo1.Text = "2" Then Call setButton(Command2) Else Call setButton(Command3) End IfEnd SubPrivate Sub setButton(cmd1 As CommandButton) cmd1.Visible = True cmd1.Enabled = TrueEnd Sub
