Question

我正在尝试在循环中执行ifs。编译器说“发生了未处理的异常”。有任何想法吗？评论的代码正在运行。中的一个不是。 for应该是更优化的。编辑：对不起忘了说所有的ComboBox和TetBox都在数组中。

        ComboBox[] ComboBoxes = new ComboBox[3];
        ComboBoxes[0] = comboBox1;
        ComboBoxes[1] = comboBox2;
        ComboBoxes[2] = comboBox3;

工作代码：

if (comboBox1.Text == "Cheese" || comboBox1.Text == "Vegetable" || comboBox1.Text == "Meat")
{
    if (comboBox2.Text == "Cheese" || comboBox2.Text == "Vegetable" || comboBox2.Text == "Meat")
    {
        if (comboBox3.Text == "Cheese" || comboBox3.Text == "Vegetable" || comboBox3.Text == "Meat")
        {
            return true;
        }
        else { comboBox3.Text = "Wrong input"; return false; }
     }
     else { comboBox2.Text = "Wrong input"; return false; }
 }
 else { comboBox1.Text = "Wrong input"; return false; }

最佳无效版本：

int isvalid = 0;

for (int i = 0; i < 3; i++)
{
    if (ComboBoxes[i].Text == "Cheese" || ComboBoxes[i].Text == "Vegetable" || ComboBoxes[i].Text == "Meat")
    {
        isvalid++;
    }
    else { ComboBoxes[i].Text = "Wrong input"; }
}

if (isvalid == 3)
{ 
    return true; 
}
else { return false; }

Answer 1

int isvalid = 0;
List<string> foods = new List<string> { "Cheese", "Vegetable", "Meat" };
List<string> cbNames = new List<string> { "comboBox1", "comboBox2", "comboBox3" }; //If you have more than the three comboBoxes
foreach(Control cb in this.Controls)
{
    if(cb is ComboBox)
    {
        if(foods.Contains((ComboBox)cb.Text) &&  cbNames.Contains((ComboBox)cb.Name))
        //Only use the second condition if you have more than the three comboBoxes
            isvalid++;
        else
            (ComboBox)cb.Text = "Wrong Input";
    }
}
if (isvalid == 3)
    return true;

return false;

这使用foreach，cb来自int isvalid = 0; List<string> foods = new List<string> { "Cheese", "Vegetable", "Meat" }; foreach(ComboBox cb in ComboBoxes) { if(foods.Contains(cb.Text)) isvalid++; else cb.Text = "Wrong Input"; } if (isvalid == 3) return true; return false;，它与循环每个组合框相同，here's some more info on foreach

在您最近的编辑后，现在可以更好地使用

  var map, GeoMarker;

  function initialize() {
    var mapOptions = {
      zoom: 17,
      center: new google.maps.LatLng(-34.397, 150.644),
      mapTypeId: google.maps.MapTypeId.ROADMAP
    };
    map = new google.maps.Map(document.getElementById('map_canvas'),
        mapOptions);

    GeoMarker = new GeolocationMarker();
    GeoMarker.setCircleOptions({fillColor: '#808080'});

    google.maps.event.addListenerOnce(GeoMarker, 'position_changed', function() {
      map.setCenter(this.getPosition());
      map.fitBounds(this.getBounds());
    });

    google.maps.event.addListener(GeoMarker, 'geolocation_error', function(e) {
      alert('There was an error obtaining your position. Message: ' + e.message);
    });

    GeoMarker.setMap(map);

if语句的优化

1 个答案: