Question

Firstly, thanks a ton to the StackOverflow community. I am new to C#, and this group has pulled me out of the fire many times!

Issue: I am having a bit of trouble with the C# FindAll method. Specifically, I can’t make it work, and I know it is me…

Stuff that works fine:

public class City
{
   public string Name {get;set;}
   public string Country {get;set;}
}

public List<City> GetCities()
{
   List<City> cities = new List<City>();
   cities.Add(new City() { Name = "Istanbul", Country = "Turkey" });
   // etc, add a bunch more cities, including multiple entries for 
   // some cities
   return cities;
}

Now what doesn’t work… (It returns all the cities or none (depending on how I fiddle the syntax).

public static List<> ReturnCityList(string CityName)
{
  Cities = GetCities;
  var RequestedCities = Cities.Findall(s => Name.Equals(CityName));
  return RequestedCities
}

What am I doing wrong?

I have read a lot of examples, but am missing something.

Thank you!

Answer 1

var RequestedCities = Cities.Findall(s => Name.Equals(CityName));

Where is Name coming from? Did you mean this?

var RequestedCities = Cities.Findall(s => s.Name.Equals(CityName));

Or even

var RequestedCities = Cities.Findall(s => s.Name == CityName);

Which does the same thing with a simpler syntax.

You aren’t using the s variable, i.e., the variable that holds the current element in the iteration. That’s what you likely need to check against CityName. I doubt your version even compiles. Also…

public static List<> ReturnCityList(string CityName)

That won’t compile. You can’t use an empty generic argument, you need to specify the return value as List<City> and then you will need to call ToList() on the result of the query. There are a couple other errors as well.

Honestly you should probably just return an IEnumurable<City> as the caller probably doesn’t need to modify the return value, just enumerate it.

One more nitpick; method arguments use camelCase by convention, not PascalCase, as do local variables.