Operator '==' cannot be applied to operands of type 'char' and 'string' <p>I have a registration application which has the "KeyChar" event inside it, and it works great ! but when i give the same lines of code in this application it gives me <code>Operator '=='/'!=' cannot be applied to operands of type 'char' and 'string'</code></p> <p>Can't seem to figure out why it works in the other application but not here! Any help is much appreciated !</p> <pre><code> private void textBox1_KeyPress(object sender, KeyPressEventArgs e) { SqlConnection DBConnection = new SqlConnection("Data Source=DATABASE;Initial Catalog=imis;Integrated Security=True"); SqlCommand cmd = new SqlCommand(); Object returnValue; string txtend = textBox1.Text; //string lastChar = txtend.Substring(txtend.Length - 1); if (e.KeyChar == "L") { DBConnection.Open(); } if (DBConnection.State == ConnectionState.Open) { if (textBox1.Text.Length != 7) return; { //cmd.CommandText = ("SELECT last_name +', '+ first_name +'\t ('+major_key+')\t' from name where id =@Name"); cmd.CommandText = ("SELECT last_name +', '+ first_name from name where id =@Name"); cmd.Parameters.Add(new SqlParameter("Name", textBox1.Text.Replace(@"L", ""))); cmd.CommandType = CommandType.Text; cmd.Connection = DBConnection; // sqlConnection1.Open(); returnValue = cmd.ExecuteScalar() + "\t (" + textBox1.Text.Replace(@"L", "") + ")"; DBConnection.Close(); if (listBox1.Items.Contains(returnValue)) { for (int n = listBox1.Items.Count - 1; n &gt;= 0; --n) { string removelistitem = returnValue.ToString(); if (listBox1.Items[n].ToString().Contains(removelistitem)) { listBox1.Items.RemoveAt(n); //listBox1.Items.Add(removelistitem+" " +TimeOut+ Time); } } } else listBox1.Items.Add(returnValue); System.IO.StreamWriter SaveFile = new System.IO.StreamWriter(fullFileName); foreach (object item in listBox1.Items) SaveFile.WriteLine(item.ToString()); SaveFile.Flush(); SaveFile.Close(); textBox1.Clear(); if (listBox1.Items.Count != 0) { DisableCloseButton(); } else { EnableCloseButton(); } Current_Attendance_Label.Text = "Currently " + listBox1.Items.Count.ToString() + " in attendance."; e.Handled = true; } } ///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////// else ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////// { returnValue = textBox1.Text.Replace(@"*", ""); if (e.KeyChar == "*") return; { if (listBox1.Items.Contains(returnValue)) { for (int n = listBox1.Items.Count - 1; n &gt;= 0; --n) { string removelistitem = returnValue.ToString(); if (listBox1.Items[n].ToString().Contains(removelistitem)) { //listBox1.Items.RemoveAt(n); } } } else listBox1.Items.Add(returnValue); textBox1.Clear(); System.IO.StreamWriter SaveFile = new System.IO.StreamWriter(fullFileName); foreach (object item in listBox1.Items) SaveFile.WriteLine(item.ToString()); SaveFile.Flush(); SaveFile.Close(); if (listBox1.Items.Count != 0) { DisableCloseButton(); } else { EnableCloseButton(); } Current_Attendance_Label.Text = "Currently " + listBox1.Items.Count.ToString() + " in attendance."; e.Handled = true; } } } </code></pre>