And again, out of range

[briley]

Let's go to the initialization of DataGridView. ♪ ♪

Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
Dim arr() As Integer
Dim j, i, length As Integer
Dim number As Integer
Dim nullCount, positiveCount, negativeCount As Integer

While length <= 0
    length = InputBox("Введите длину массива (неотрицательное ненулевое число):")
End While

ReDim arr(0 To length)

For j = 0 To length - 1
    number = InputBox("Введите целое число (отрицательное или положительное).")
    If IsNumeric(number) Then
        arr(j) = number
    Else
        j -= 1
        MsgBox("Вводите число!")
    End If
Next j

DataGridView1.ColumnCount = length
DataGridView1.RowCount = 1
negativeCount = 0
nullCount = 0
positiveCount = 0


For i = 0 To length - 1
    DataGridView1.Item(1, i).Value = arr(i)
    If arr(i) > 0 Then
        positiveCount += 1
    ElseIf arr(i) Like 0 Then
        nullCount += 1
    Else
        negativeCount += 1
    End If
Next i

Label1.Text = "Количество отрицательных элементов: " + negativeCount.ToString()
Label2.Text = "Количество нулевых элементов: " + nullCount.ToString()
Label3.Text = "Количество положительных элементов: " + positiveCount.ToString()

Me.Opacity = 100

End Sub

[chanisef]

DataGridView1.Item(i, 0).value = arr(i)You have RowCount=1, followed by. 0and change the indices to the locations, it must be. Reference https://msdn.microsoft.com/ru-ru/library/ms158656(v=vs.110).aspx

Public Property Item (
  columnIndex As Integer,
  rowIndex As Integer
) As DataGridViewCell