StringBuilder extension method to add collection in C #

Question

In C #, I am trying to create an extension method for StringBuilder called AppendCollection () that will allow me to do this:

var sb1 = new StringBuilder();
var sb2 = new StringBuilder();
var people = new List<Person>() { ...init people here... };
var orders = new List<Orders>() { ...init orders here... };

sb1.AppendCollection(people, p => p.ToString());
sb2.AppendCollection(orders, o => o.ToString());

string stringPeople = sb1.ToString();
string stringOrders = sb2.ToString();

stringPeople will contain a string for each person in the list. Each row will be the result of p.ToString (). Similarly for stringOrders. I'm not quite sure how to write code to make lambdas work with generics.

Answer 1

Use a delegate Func<T,string>.

public static void AppendCollection<T>(this StringBuilder sb, 
                                       IEnumerable<T> collection, Func<T, string> method) {
   foreach(T x in collection) 
       sb.AppendLine(method(x));
}

Answer 2

 public static void AppendCollection<T>(this StringBuilder builder, IEnumerable<T> list, Func<T,string> func)
        {
            foreach (var item in list)
            {
                builder.AppendLine(func(item));
            }
        }

I would not return the string, I just add it to the original Stringbuilder that was passed.

Answer 3

, :

 public static void AppendCollection( this StringBuilder builder,
                                      ICollection collection )
 {
     foreach (var item in collection)
     {
        builder.AppendLine( Convert.ToString( item ) );
     }
 }

 List<Person> people = ...

 StringBuilder builder = new StringBuilder();
 builder.AppendCollection( people );
 var s = builder.ToString();

, Person ToString() Person.

Answer 4

- :

  public static void AppendCollection<TItem>(this StringBuilder builder, IEnumerable<TItem> items, Func<TItem, string> valueSelector)
  {
       foreach(TItem item in items)
       {  
            builder.Append(valueSelector(item));
       }
  }

, 90% ...

   public static void AppendCollection<TItem>(this StringBuilder builder, IEnumerable<TItem> items)
  {
      AppendCollection(builder, items, x=>x.ToString());
   }

Answer 5

:

    public static string AppendCollection<T>(this StringBuilder sb, IEnumerable<T> enumerable, Func<T, string> method)
    {
        List<T> l = new List<T>(enumerable);
        l.ForEach(item => sb.AppendLine(method(item)));
        return sb.ToString();
    }

. :

    public static void AppendCollection<T>(this StringBuilder sb, IEnumerable<T> enumerable, Func<T, string> method)
    {
        List<T> l = new List<T>(enumerable);
        l.ForEach(item => sb.AppendLine(method(item)));
    }

:

        sb.AppendCollection(people, p => p.ToString());
        sb.AppendCollection(orders, o => o.ToString());
        Console.WriteLine(sb.ToString());

Answer 6

? , , StringBuilder?

, , , , .

:

. , StringBuilder .

2:

, , , , - . , , - :

public static string Print<T>(this IEnumerable<T> col, Func<T,string> printer)
{
  var sb = new StringBuilder();
  foreach (T t in col)
  {
    sb.AppendLine(printer(t));
  }
  return sb.ToString();
}

string[] col = { "Foo" , "Bar" };
string lines = col.Print( s => s);

3:

:

public static void AppendCollection<T>(this StringBuilder sb, 
   List<T> col, Func<T,string> printer)
{
  col.ForEach( o => sb.AppendLine(printer(o)));
}

( , bruno conde)

:)

Answer 7

static class SBExtention
{
  static string AppendCollection<T>(this StringBuilder sb, 
                                    IEnumerable<T> coll, 
                                    Func<T,string> action)
  {
       foreach(T t in coll)
       {
          sb.Append(action(t));
          sb.Append("\n");
       }
       return sb.ToString();

  }
}

However, I think you would be better off returning a StringBuilder. So you can link it:

  static StringBuilder AppendCollection<T>(this StringBuilder sb, 
                                    IEnumerable<T> coll, 
                                    Func<T,string> action)
  {
       // same
       return sb;

  }

string peopleAndOrders = sb.AppendCollection (people, p => p.ToString ()) .AppendCollection (orders, o => o.ToString ()). ToString ();

And I agree with Jennifer about the default case:

   public static StringBuilder AppendCollection<TItem>(
                  this StringBuilder builder, 
                  IEnumerable<TItem> items)
  {
      return AppendCollection(builder, items, x=>x.ToString());
   }

string peopleAndOrders = sb.AppendCollection (people) .AppendCollection (orders) .ToString ();