[英]Why are none of my form's controls being recognized as being ComboBoxes?
I'm making a combobox "readonly" in this way: 我以这种方式使组合框“只读”:
private void comboBox1_SelectedValueChanged(object sender, EventArgs e)
{
// for this to work, set the comboboxes' Tag to its SelectedIndex after setting that
ComboBox cb = sender as ComboBox;
int validSelection = Convert.ToInt32(cb.Tag);
if (cb.SelectedIndex != validSelection )
{
cb.SelectedIndex = validSelection;
}
}
...and then trying to set all of the comboboxes on the form to that handler like this: ...然后尝试将表单上的所有组合框设置为该处理程序,如下所示:
foreach (Control c in this.Controls)
{
if (c is ComboBox)
{
(c as ComboBox).SelectedValueChanged += comboBox1_SelectedValueChanged;
}
}
...but the if condition is never equating to true; ...但是if条件永远不等于true; there are several ComboBoxes on the form...???
表格上有几个组合框... ???
The ComboBoxes are most likely inside other panels. 组合框很可能在其他面板中。
Try going through them recursively: 尝试递归地遍历它们:
private void button1_Click(object sender, EventArgs e) {
ChangeCombos(this);
}
private void ChangeCombos(Control parent) {
foreach (Control c in parent.Controls) {
if (c.Controls.Count > 0) {
ChangeCombos(c);
} else if (c is ComboBox) {
(c as ComboBox).SelectedValueChanged += comboBox1_SelectedValueChanged;
}
}
}
step though it set a breakpoint on the begin { and call c.gettype() 尽管它在开始{上设置了一个断点,并调用c.gettype()
also you might want to do this 你也可能想这样做
if( c.gettype() == typeof(ComboBox))
{
}
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