# Answer to Exercise 8

Like exercise 7, we split the **numbers** variable to create an array. The
outer for loop grabs 1 number at a time from the array. The inner loop then
checks the rest of the numbers to see if there is a match. But have a look at
the initialisation of the inner loop:

int j = i + 1

The **j** variable is being set to whatever value **i** is (the outer
loop) plus 1. This ensures that you're not checking the numbers from the start
of the array all the time. You're checking only in a forwards direction. For
example, suppose i has a value 0. This would grab the number 9 from our array.
The inner loop would set j to i + 1, which is a value of 1. So the inner loop
would check the numbers from 8 to the end of the array, which is 6. If a match
is found then we can increment the counter. The next time round the outer loop,
the number from the array would be 8. The inner loop would then set j to be
i + 1, which is 2. Which means that the inner loop checks the numbers 7, 8 and
6 looking for a match.

### C# NET Answer

private void btnPairs_Click(object sender, EventArgs e) { string numbers = "9-8-7-8-6"; string[] array_numbers = numbers.Split('-'); int counter = 0; for (int i = 0; i < array_numbers.Length - 1; i++) { string pair_check = array_numbers[i]; for (int j = i + 1; j < array_numbers.Length; j ++) { if (pair_check == array_numbers[j]) { counter++; } } } if (counter > 0) { MessageBox.Show("At least one pair found"); } }

### VB NET Answer

Private Sub btnPairs_Click(sender As Object, e As EventArgs) Handles btnPairs.Click Dim numbers = "9-8-7-8-6" Dim array_numbers() As String array_numbers = numbers.Split("-") Dim counter As Integer = 0 For i = 0 To array_numbers.Length - 1 Dim pair_check = array_numbers(i) For j = i + 1 To array_numbers.Length - 1 If pair_check = array_numbers(j) Then counter = counter + 1 End If Next Next If counter > 0 Then MessageBox.Show("At least one pair found") End If End Sub

### Java Answer

public static void main(String[] args) { String numbers = "9-8-5-7-8"; String[] array_numbers = numbers.split("-"); int counter = 0; for (int i = 0; i < array_numbers.length - 1; i++) { String pair_check = array_numbers[i]; for (int j = i + 1; j < array_numbers.length; j ++) { if (pair_check.equals(array_numbers[j])) { counter++; } } } if (counter > 0) { System.out.println("At least one pair found"); } }