CODEWITHSUNDEEP
c#nullreferenceexception
Natasha Thapa
Natasha Thapa

Reputation: 969

NullReferenceException While Populating an Array

[DataContract]
public class PersonField
{
    private string _fieldName;
    private object _fieldValue;

    public PersonField()
    {
    }

    public PersonField(string FieldName, object FieldValue)
    {
        _fieldName = FieldName;
        _fieldValue = FieldValue;
    }
    [DataMember]
    public string FieldName
    {
        get { return _fieldName; }
        set { _fieldName = value; }
    }
    [DataMember]
    public object FieldValue
    {
        get { return _fieldValue; }
        set { _fieldValue = value; }
    }
}

I have this class above which is used in my WCF service. when i try to create array on client side for this like

PersonField[] test = new PersonField[2];
test[0].FieldName = "test";

i get Object reference not set to an instance of an object. not sure what am i doing wrong?

Upvotes: 0

Views: 292

Answers (2)

Amit
Amit

Reputation: 22076

For this you have to do this. Yo need to initialize test[0] with new keyword as well.

PersonField[] test = new PersonField[2];
test[0] = new  PersonField();
test[0].FieldName = "test";
test[1] = new  PersonField();
test[1].FieldName = "test2";

Value Type and Reference Type Arrays

Consider the following array declaration: C#

SomeType[] array4 = new SomeType[10];

The result of this statement depends on whether SomeType is a value type or a reference type. If it is a value type, the statement results in creating an array of 10 instances of the type SomeType. If SomeType is a reference type, the statement creates an array of 10 elements, each of which is initialized to a null reference.

For more information on value types and reference types, see Types (C# Reference).

Here is MSDN link

Upvotes: 0

Reed Copsey
Reed Copsey

Reputation: 564383

Since this is a class, you're creating an array of references, not the actual objects. You still need to allocate the instance(s) yourself:

PersonField[] test = new PersonField[2];
test[0] = new PersonField();
test[0].FieldName = "test";
test[1] = new PersonField();

Upvotes: 3

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