只能输入数字+字母+下划线

if (e.KeyChar >= (char)Keys.D0 && e.KeyChar <= (char)Keys.D9 || (e.KeyChar >= 'A' && e.KeyChar <= 'Z') || (e.KeyChar >= 'a' && e.KeyChar <= 'z') || e.KeyChar == '_' || e.KeyChar == '-' || e.KeyChar == (char)Keys.Back || e.KeyChar == (char)Keys.Delete) { e.Handled = false; } else { e.Handled = true; }