A very, very simple C# question.
I want to create a normal little array of a type that is another class.
bits of the code:
class Program
{
static void Main(string[] args)
{
classA[] test;
test = new classA[2];
Console.Write(test[0].getName());
class classA
{
string name;
public classA()
{
this.name = "zup";
}
public string getName()
{
return this.name;
}
Why wont it let me ?
When you create an array of a reference type like that, the array is initialised with nulls - no actual objects are constructed (other than the array itself).
Therefore you need to explicitly create each element of your array.
For your example, you will need to do this:
classA[] test;
test = new classA[2];
test[0] = new classA();
test[1] = new classA();
Note that if you were using a value type such as a struct or a primitive type (int, double, char etc) this would not be necessary.
You often write a loop to initialise an array, so again for your code sample:
classA[] test;
test = new classA[2];
for (int i = 0; i < test.Count; ++i)
test[i] = new classA();
You create an array of type ClassA, but don't initalize the elements, so the elements in the array are all null. To make a simple test array, with content, use an array initializer instead:
var test = new ClassA[] { new ClassA(), new ClassA() };
you can do it as below
test = new classA[2].Select(c=>new classA()).ToArray();
after you call new classA[2] you have null items in the array. above code will add new ClassA object to each array item. Now you can call Console.Write(test[0].getName()); without exception
test[0].getName()should lead to aNullReferenceException.