检查字符串是否包含任何字符串数组值，然后获取子字符串

Question

This may be a sub-question to this SO Question . I want to check the string against an array of string or list. Example

string address = "1st nice ave 1st floor";    
//For now, I'm getting the list from a text file but could move to use an EF    
List<string> streetType = File.ReadLines(AppDomain.CurrentDomain.BaseDirectory + @"streetType.csv")
                              .Where(x => x.Length > 0)
                              .Select(y => y.ToLowerInvariant())
                              .ToArray();

the purpose is to strip the extra address details after the avenue, the csv file contains all USPS accepted street type.

This is what I have now

//this only returns boolean value, I got this from the SO above
streetType.Any(testaddress.ToLower().Contains);

//I also have this
Array.Exists<string>(streetType, (Predicate<string>)delegate (string s)
{         
   return testaddress.IndexOf(s, StringComparison.OrdinalIgnoreCase) > -1;       
});

I've been looking for hours how to resolve this then I came across the SO question which is exactly what I also want but I need to get the substring to for stripping.

If there's a linq query, that would be awesome. The only way I can think of doing this is with foreach and inner if.

Example of the array values

• ave
• avenue
• pkwy

Update:

Here is my answer, I forgot to mention that the array lookup needs to match the exact string from the address string. I ended up using regex. This is the expanded/modified answer of @giladGreen.

  var result = from item in streetTypes
                         let index = Regex.Match(address.ToLowerInvariant(), @"\b" + item.ToLowerInvariant() + @"\b")
                         where index.Success == true
                         select address.ToLowerInvariant().Substring(0, index.Index + item.Length);

Can somebody convert this to lambda expression? I tried I failed.

Thank you all

Answer 1

Use IndexOf to understand of item is present in address and if so to return the string after it:

var result = from item in streetType
             let index = address.IndexOf(item)
             where index != -1
             select address.SubString(0, index);

Answer 2

One way to do this would be to simply Split each address on the streetType list, and then take the first item (at index[0] ) from the resulting array:

addresses = addresses
    .Select(address => address.Split(streetTypes.ToArray(), StringSplitOptions.None)[0])
    .ToList();

Answer 3

I might be inclined to do something like this:

string[] markers = "ave avenue pkwy".Split();
string address = "1st nice ave 1st floor";

var result = markers
            .Select((marker, index) => new
            {
                markerIndex = index,
                addressPosition = address.IndexOf(marker)
            })
            .FirstOrDefault(x => x.addressPosition != -1);


// returns { markerIndex = 0, addressPosition = 9 }

Then result is an object that is either null (if the marker is not found) or is an object containing both markerIndex , which tells you which marker was found first, and addressPosition which tells you the character at which the marker string was found.