How to declare an array of objects in C

Question

I have a very beginning C  question  Suppose I have a class called GameObject  and I want to create an array of GameObject entities  I could think of writing code like  GameObject   houses   new GameObject 200    The compiler complains  assuming because of invalid syntax   Since this is XNA development  I load my texture in the LoadContent   method as follows   houses 0  Model   Content Load lt Model gt   quot Models  Building 01 Windowed quot     where houses 0  should be a GameObject and can be loaded like this  but the compiler throws this error    quot Use the  quot new quot  keyword to create an object instance quot   quot Check to determine if the object is null before calling the method quot   There must be something wrong with my initialization

User · Answer

You are creating an array of null references  You should do something like   for  int i   0  i  lt  houses Count  i          houses i    new GameObject

User · Answer

The reason this is happening is because initializing an array does not initialize each element in that array  You need to first set houses 0    new GameObject   and then it will work

User · Answer

The issue here is that you ve initialized your array  but not its elements  they are all null  So if you try to reference houses 0   it will be null   Here s a great little helper method you could write for yourself   T   InitializeArray lt T gt  int length  where T   new         T   array   new T length       for  int i   0  i  lt  length    i                array i    new T               return array      Then you could initialize your houses array as   GameObject   houses   InitializeArray lt GameObject gt  200

User · Answer

With LINQ  you can transform the array of uninitialized elements into the new collection of created objects with one line of code   var houses   new GameObject 200  Select h   gt  new GameObject    ToArray      Actually  you can use any other source for this  even generated sequence of integers   var houses   Enumerable Repeat 0  200  Select h   gt  new GameObject    ToArray      However  the first case seems to me more readable  although the type of original sequence is not important

User · Answer

Everything you have looks fine     The only thing I can think of  without seeing the error message  which you should have provided   is that GameObject needs a default  no parameter  constructor

User · Answer

you need to initialize the object elements of the array    GameObject   houses   new GameObject 200    for  int i 0  i lt house  i lt houses length  i      houses i    new GameObject       Of course you initialize elements selectively using different constructors anywhere else before you reference them

User · Answer

I guess GameObject is a reference type  Default for reference types is null    you have an array of nulls   You need to initialize each member of the array separatedly   houses 0    new GameObject        Only then can you access the object without compilation errors   So you can explicitly initalize the array   for  int i   0  i  lt  houses Length  i          houses i    new GameObject        or you can change GameObject to value type

[c#] How to declare an array of objects in C#

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