by Keyvan Nayyeri via Keyvan Nayyeri on 10/4/2006 2:33:00 PM
Notice the usage of List<T>.ConvertAll() method in my previous post:
public String Points
{
get
return String.Join(" | ",
(String[])this.myStudent.Points.ConvertAll
(new Converter<Double, String>(delegate(Double value)
return Convert.ToString(value);
}
)).ToArray());
Who has said we should write a simple code?!! I used List<T>.ConvertAll() function to get a List<String> from a List<Double> then converted my List<String> to an Array of Strings.
List<T>.ConvertAll() method is a new .NET 2.0 Generic method which gets a System.Converter object and converts each element in a List<T> from type T to the outgoing type. It seems this method is using a predicate but actually it doesn't do this.
ConvertAll() method gets a Converter object which converts each item from incoming type to outgoing type. Converter gets a delegate as its parameters. This logic for this delegate must convert an incoming value of first type to the second type and return it. In above example I used anonymous method to save my time.
For better understanding of this method you can take a look at following Console Application example. I used simpler code and divided my code to more steps to let you know what's going on.
static void Main(string[] args)
// Set Initial Data
List<Double> numbers = new List<Double>();
for (int i = 0; i < 10; i++)
numbers.Add(i + 0.25);
// Define a Converter
Converter<Double, String> converter =
new Converter<Double, String>(delegate(Double value)
});
String[] strNumbers;
// Convert a List<String> to Array of Strings
strNumbers = (String[])numbers.ConvertAll(converter).ToArray();
// Show the Output
Console.WriteLine(String.Join(" ", strNumbers));
Console.ReadLine();
First a List<Double> is created then using a Converter this List<Double> is converted to List<String> and finally List<String> is converted to Array of Strings and has been sent to output.
Original Post: List.ConvertAll<>()
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