我有一个If Else语句,要从当前位置中获得最近的位置,这意味着第一个位置为空(不存在),并且根据第一个位置的最小距离来计算第二个位置。在其他部分中,我将通过使用Math.Min将当前站点的距离与已知的最小距离进行比较。但是,我缺少在Else语句中存储结果和分配当前电台的功能。我的问题所在的位置是第14和15行。
class City : ICity
{
private List<Company> _companies;
private List<Line> _lines;
private List<Station> _stations;
internal City(string name)
{
this.Name = name;
_companies = new List<Company>();
_lines = new List<Line>();
_stations = new List<Station>();
}
public string Name{get;}
public ILine AddLine(string name){...}
public IStation AddStation(string name, int x, int y){...}
public IStation FindNearestStation(int x, int y)
{
int ? minDist = null;
Station minStation=null;
foreach (var station in _stations)
{
int dis = GetDistancebtween(x1: station.X, y1: station.Y, x2: x, y2: y);
if (!minDist.HasValue || dis < minDist.Value)
{
minDist = dis;
minStation = station;
}
}
return minStation;
}
private int GetDistancebtween(int x1, int y1, int x2, int y2)
{
return (x1 - x2) ^ 2 + (y1 - y2) ^ 2;
}
}
单元测试在第10行中断。
public void city_returns_effectively_the_closest_station()
{
ICity c = CityFactory.CreateCity("Paris");
IStation s = c.AddStation("Opera", 0, 0);
IStation s1 = c.AddStation("Chatelet", 10, 10);
c.FindNearestStation(-10, -10).Should().BeSameAs(s);
//test does not pass in this position
c.FindNearestStation(10, 10).Should().BeSameAs(s1);
c.FindNearestStation(15, 15).Should().BeSameAs(s1);
}
如果更改minDist值,则还应该更改minStation值。在else块内而不是Math.Min内使用简单的if可以解决问题。
....
else
{
if(dis < minDist.Value)
{
minDist = dis;
minStation = station;
}
}
并且这将导致不使用else块而进行进一步的更改
foreach (var station in _stations)
{
var dis = GetDistancebtween(x1: x, y1: y, x2: station.X, y2: station.Y);
if(!minDist.HasValue || dis < minDist.Value)
{
minDist = dis;
minStation = station;
}
}