我不想只在C＃中的文本框中输入空格，而是在空格中输入charector。这是我的错误代码。 [英] I dont want to enter only spaces in textbox in C# but charector with spaces ok. Here is my code with errors.

问题描述

 private void btnsave_Click（object sender，EventArgs e）
 {
 if（comboslm.Text ==）
 {
 
 MessageBox.Show（请选择推销员名称）; 
 
 comboslm.Focus（）; 
} 
 否则if（slmname.Text ==|| slmname.Text ==！char.IsWhiteSpace（e.KeyChar）） （这里只有红线显示。也无法渲染。）  
 {
 
 MessageBox.Show（空的推销员名称不被接受）; 
 slmname.Focus（）; 
 
} 
 else if（combosmancode.Text ==）
 {
 MessageBox.Show（Select Record Key Number）; 
 combosmancode.Focus（）; 
} 
 else 
 {
 SqlConnection con = new SqlConnection（@Data Source = M2\SQL2016; Initial Catalog = inventoryDB; Integrated Security = True）; 
 con.Open（）; 
 SqlCommand cmd = new SqlCommand（UPDATE smanDB SET smaname = @ label2 WHERE smancode = @ label4，con）; 
 cmd.Parameters.Add（@ label2，slmname.Text）; 
 cmd.Parameters.Add（@ label4，combosmancode.GetItemText（combosmancode.SelectedItem））; 
 cmd.ExecuteNonQuery（）; 
 con.Close（）; 
 MessageBox.Show（已成功更新）; 
 / * combosmancode.SelectedIndex = -1; 
 comboslm.SelectedIndex = -1; 
 slmname.Text =; 
 comboslm.Focus（）; * / 
 con = new SqlConnection（@Data Source = M2\SQL2016; Initial Catalog = inventoryDB; Integrated Security = True）; 
 con.Open（）; 
 string query =SELECT smaname FROM smanDB; 
 string que =SELECT smancode FROM smanDB; 
 SqlDataAdapter da = new SqlDataAdapter（query，con）; 
 SqlDataAdapter sda = new SqlDataAdapter（que，con）; 
 DataSet ds = new DataSet（）; 
 DataSet sds = new DataSet（）; 
 da.Fill（ds，smanDB）; 
 sda.Fill（sds，smanDB）; 
 comboslm.DisplayMember =smaname; 
 comboslm.ValueMember =smaname; 
 comboslm.DataSource = ds.Tables [smanDB]; 
 
 combosmancode.DisplayMember =smancode; 
 combosmancode.ValueMember =smancode; 
 combosmancode.DataSource = sds.Tables [smanDB]; 
 
 combosmancode.SelectedIndex = -1; 
 comboslm.SelectedIndex = -1; 
 slmname.Text =; 
 con.Close（）; 
 

我的尝试：



我试图检查空。我成功了。但是对于空格只有它显示错误。有空格的charector也行。但是只防止显示错误的空格

解决方案

  else   if （slmname.Text ==   || slmname .Text ==！char.IsWhiteSpace（e.KeyChar））

该声明的后半部分是错误的。您无法将文本字段（ slmname.Text ）与布尔值（！char.IsWhiteSpace（e.KeyChar））。

private void btnsave_Click(object sender, EventArgs e)
       {
           if(comboslm.Text == "")
           {

               MessageBox.Show("Please Select Salesman Name");

               comboslm.Focus();
           }
          else if(slmname.Text=="" || slmname.Text==!char.IsWhiteSpace(e.KeyChar)) (Here only redline it is showing.So unable to render also)
           {

               MessageBox.Show("Empty Salesman Name Not Accepted");
               slmname.Focus();

           }
           else if (combosmancode.Text == "")
           {
               MessageBox.Show("Select Record Key Number");
               combosmancode.Focus();
           }
           else
           {
               SqlConnection con = new SqlConnection(@"Data Source=M2\SQL2016;Initial Catalog=inventoryDB;Integrated Security=True");
               con.Open();
               SqlCommand cmd = new SqlCommand("UPDATE smanDB SET smaname=@label2 WHERE smancode=@label4", con);
               cmd.Parameters.Add("@label2", slmname.Text);
               cmd.Parameters.Add("@label4", combosmancode.GetItemText(combosmancode.SelectedItem));
               cmd.ExecuteNonQuery();
               con.Close();
               MessageBox.Show("Updated Successfully");
              /* combosmancode.SelectedIndex = -1;
               comboslm.SelectedIndex = -1;
               slmname.Text = "";
               comboslm.Focus();*/
               con = new SqlConnection(@"Data Source=M2\SQL2016;Initial Catalog=inventoryDB;Integrated Security=True");
               con.Open();
               string query = "SELECT smaname FROM smanDB";
               string que = "SELECT smancode FROM smanDB";
               SqlDataAdapter da = new SqlDataAdapter(query, con);
               SqlDataAdapter sda = new SqlDataAdapter(que, con);
               DataSet ds = new DataSet();
               DataSet sds = new DataSet();
               da.Fill(ds, "smanDB");
               sda.Fill(sds, "smanDB");
               comboslm.DisplayMember = "smaname";
               comboslm.ValueMember = "smaname";
               comboslm.DataSource = ds.Tables["smanDB"];

               combosmancode.DisplayMember = "smancode";
               combosmancode.ValueMember = "smancode";
               combosmancode.DataSource = sds.Tables["smanDB"];

               combosmancode.SelectedIndex = -1;
               comboslm.SelectedIndex = -1;
               slmname.Text = "";
               con.Close();

What I have tried:

I tried to check empty. I succeeded. But for spaces only then it showing error. charector with spaces also ok. But prevent only spaces showing error

解决方案

else if(slmname.Text=="" || slmname.Text==!char.IsWhiteSpace(e.KeyChar))

The second half of that statement is wrong. You cannot compare a text field (slmname.Text) to a boolean value (!char.IsWhiteSpace(e.KeyChar)).

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