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String concatenation C# with List of Class

this may be very fundamental C# question as I only study C# myself there are things that I do not have the logic to start.

I have a class CustomerSite with string Customer get;set and string Site get;set;

CustomerSite

string Customer get;set

string Site get;set;

I create a list List<CustomerSite> listCustomerSite= new List<CustomerSite>();

List<CustomerSite> listCustomerSite= new List<CustomerSite>();

Assume, I have a list with the following data

SAMSUNG CHINA
SAMSUNG AMERICA
SAMSUNG AFRICA
LG CHINA
APPLE AMERICA
APPLE CHINA


I would like to have 1 concatenated string

string Result = "APPLE (AMERICA, CHINA), LG (CHINA), SAMSUNG (AFRICA, AMERICA, CHINA)"

string Result = "APPLE (AMERICA, CHINA), LG (CHINA), SAMSUNG (AFRICA, AMERICA, CHINA)"

How could I do that?

My idea is to use a dictionary to keep a list of distinct Customers and adding the site to the string but I still have no clue how to deal with sorting (AFRICA --> AMERICA --> CHINA)

(AFRICA --> AMERICA --> CHINA)

Dictionary<string, int> dictCustomer = new Dictionary<string, int>();
foreach (var i in listCustomerSite)

if (!dictCustomer.ContainsKey(i.Customer))

dictCustomer.Add(i.Customer, 0);
Result = Result + "," + "i.Customer" + "( i.Site) ";

else

Result.Replace(")", "," + i.Site + ")");




4 Answers
4

You can utilize LINQ and String.Join to group your collection by customer, convert each grouping to a formatted string with sorted comma-separated sites, and then combine them to a single string:

String.Join

var customersWithLocations = listCustomerSite
.GroupBy(cs => cs.Customer)
.Select(g => $"g.Key (String.Join(", ", g.Select(cs => cs.Site).OrderBy(s => s)))")
.ToArray();

string result = String.Join(", ", customersWithLocations);


.ToArray()

String.Join

IEnumerable<string>

IEnumerable<T>

.ToArray()

customersWithLocations

.OrderBy(g => g.Key)

GroupBy

A one line LINQ statment can do it all:

var list = listCustomerSite
.GroupBy(c => c.Customer)
.Select(g => $"g.Key (string.Join(", ", g.Select(c => c.Site)))")
.ToList();


"I would like to have 1 concatenated string"

This should produce the desired output, sorted as required:

public class CustomerSite

public CustomerSite(string customer, string site)

Customer = customer;
Site = site;


public string Customer get; set;

public string Site get; set;


class Program

static void Main(string args)

var listCustomerSite = new List<CustomerSite>()

new CustomerSite("SAMSUNG", "CHINA"),
new CustomerSite("SAMSUNG", "AMERICA"),
new CustomerSite("SAMSUNG", "AFRICA"),
new CustomerSite("LG", "CHINA"),
new CustomerSite("APPLE", "AMERICA"),
new CustomerSite("APPLE", "CHINA")
;

var list = from cs in listCustomerSite
group cs by cs.Customer into g
orderby g.Key
select $"g.Key (string.Join(", ", g.OrderBy(c => c.Site).Select(c => c.Site)))";

Console.WriteLine(string.Join(", ", list));
Console.ReadKey();




Output:

APPLE (AMERICA, CHINA), LG (CHINA), SAMSUNG (AFRICA, AMERICA, CHINA)


Hope this helps!

The idea of using a dictionary is good; however, I would operate in two steps:

I'm not going to use LINQ, as it will be more instructive and show the fundamental way of doing things (since you are learning C#).

I am using a SortedDictionary<TKey, TValue> as it automatically sorts the entries by the key (the customers in our case).

SortedDictionary<TKey, TValue>

var dictCustomer = new SortedDictionary<string, SortedSet<string>>();


The idea is to use the customer name as key and a sorted set of sites as value. A SortedSet<T> not only keeps the entries sorted, but also eliminates duplicates (which is not required here).

SortedSet<T>

foreach (CustomerSite customerSite in listCustomerSite)
if (dictCustomer.TryGetValue(customerSite.Customer, out var siteSet))
siteSet.Add(customerSite.Site);
else
siteSet = new SortedSet<string> customerSite.Site ;
dictCustomer.Add(customerSite.Customer, siteSet);




Now, let us build the result string:

var sb = new StringBuilder();
foreach (var keyValuePair in dictCustomer)
if (sb.Length > 0)
sb.Append(", ");

sb.Append(keyValuePair.Key).Append(" ("); // Appends the customer and " (".
bool nextSite = false;
foreach (string site in keyValuePair.Value)
if (nextSite)
sb.Append(", ");

sb.Append(site);
nextSite = true;

sb.Append(")");

string result = sb.ToString();


Note that a StringBuilder is more efficient than concatenating strings directly, since a StringBuilder uses a buffer internally which grows only as needed, while string concatenation creates a new string object at each step and involves copying an ever-growing string over and over.

StringBuilder

StringBuilder

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