Why not executing?

Question

Why following program is not executing?

using System;

class Program
{
static void Main()
{
int[] intA = {1,2,3,4,5};
string[] stringA = {"aa","bb","cc" };

A(intA);
A(stringA);

Console.ReadKey();
}
static void A(object[] x)
{
foreach (object item in x)
{
Console.WriteLine(item);

}
}
}

Vulpes · Answer

It doesn't compile because there's no conversion from int[] to object[]. If you were to comment out this line: A(intA); then you'd find that the program does compile and produce the expected output to the console: aa bb cc This is because there is a conversion from string[] to object[] as a result of something called 'array covariance'. However this only applies to arrays of reference types - it doesn't apply to arrays of value types such as int[]. For more on array covariance check out this link: http://msdn.microsoft.com/en-us/library/aa664572(v=vs.71).aspx

Maha · Answer

Thank you for your help.

Vulpes · Answer

The Enumerable.Cast extension method is part of the LINQ infrastructure. It's documented on MSDN here: http://msdn.microsoft.com/en-us/library/bb341406.aspx However unless you're wanting to learn the whole of LINQ at this point in your studies you might be better sticking to 'traditional' code for the time being: object[] k = new object[intA.Length]; for(int i = 0; i A(k);

Maha · Answer

Thanks Vulpes. I wish to know whether online resources available to learn this (object[] k = intA. Cast ().ToArray();) way of casting.

Vulpes · Answer

Just add this 'using' directive at the top of the file: using System.Linq; and it will compile and work fine.

Maha · Answer

Program is not compiling Jignesh using System; class Program { static void Main() { int[] intA = { 1 2 3 4 5 }; string[] stringA = { aa bb cc }; object[] k = intA.Cast ().ToArray(); A(k); A(stringA); Console.ReadKey(); } static void A(object[] x) { foreach (object item in x) { Console.WriteLine(item); } } }

Jignesh Trivedi · Answer

hi Agree with Vulpes. you have to convert you int array to object array... try... int[] intA = { 1 2 3 4 5 }; object[] k = intA.Cast ().ToArray(); A(k); hope this will help you.

Maha · Answer

Thanks