Question

I have a string array

public: array<String ^> ^ sss;
public:
    Form1(void)
    {
        InitializeComponent();
        //
        //TODO: Add the constructor code here
        //
        array<String ^> ^ sss = gcnew array<String ^>(3);
        sss[0]="asdasd";
        sss[1]="s115ss";
        sss[2]="s115ss";
    }

I need to show the 1st element into a textbox.

I used

private: System::Void button1_Click(System::Object^  sender, System::EventArgs^  e) {

             textBox2->Text = sss[0];
         }

Vc++ gave System.NullReferenceException. Why? And how to fix it?

The error:

An unhandled exception of type ‘System.NullReferenceException’ occurred in test000.exe
Additional information: Object reference not set to an instance of an object.

Answer 1

Your code shouldn’t compile, unless you also have a field called sss. If that’s the case, you want to set the value of that field in your constructor, not of some unrelated local variable with the same name:

array<String ^> ^ sss;

public:
    Form1(void)
    {
        InitializeComponent();

        sss = gcnew array<String ^>(3);
        sss[0]="asdasd";
        sss[1]="s115ss";
        sss[2]="s115ss";
    }