How to add value to an array of object in C#

Question

I am consuming a third party web service and I want to add value to match the service reference class, and i am not sure how to add value to the following:

in reference:

public partial class UserInfor: object, System.ComponentModel.INotifyPropertyChanged 
{
        private ABC[] listOfABCField;

        public ABC[] ListOfABC 
    {
            get {
                return this.listOfABCField;
            }
            set {
                this.listOfABCField = value;
                this.RaisePropertyChanged("ListOfABC");
            }
        }
}

public partial class ABC : object, System.ComponentModel.INotifyPropertyChanged 
{
    private string ipField;

private string fristNameField;

private string lastNameField;       

}

////////////////////////////////////////////////////// in my service.asmx file have tried to put value as below: in below code i got exception in line ABC[] abc=new ABC[0]; error code:(NullReferenceException)

    UserInfor user = new UserInfor();
    ABC[] abc=new ABC[0];
        abc[0].firstName= "petter";
        abc[0].lastName = "lee";

        user.ListOfABC = abc[1];

i also tried in below code i got exception in line user.ListOfABC[0] = abc; error code:(NullReferenceException)

    UserInfor user = new UserInfor();
    ABC abc=new ABC[0];
        abc.firstName= "petter";
        abc.lastName = "lee";

        user.ListOfABC[0] = abc;

any idea how to add abc to user class ? thank you in advance

Answer 1

This'll probably be easier if you use a List<> instead of an array. Change the property:

private List<ABC> listOfABCField;

public List<ABC> ListOfABC
{
    // etc.
}

Don't forget to initialize it in the class' constructor so it's not null:

public UserInfor()
{
    listOfABCField = new List<ABC>();
}

Then you can just add an object to it, which doesn't need any of the array syntax you were trying to use:

UserInfor user = new UserInfor();
ABC abc = new ABC();
abc.firstName= "petter";
abc.lastName = "lee";

user.ListOfABC.Add(abc);

Answer 2

You are doing it wrong, first instantiate the array, if you know in advance how many items it would contain then specify that as well in the square brackets like:

ABC[] abc=new ABC[1]; // this array will contain 1 item maximum

now instantiate that item and then set values of properties :

    abc[0] = new ABC(); // instantiating first item of array which is at 0th index
    abc[0].firstName= "petter";
    abc[0].lastName = "lee";

If you don't know how many item would come in it, then go with @David's suggestion of using List<T>