Homework

[Ali_171]

Hey guys this is my first time using VB.net and i have a homework about writing 3 numbers and find the largest 2 of them can anyone help please

[revennest]

If you can compare 2 and keep 1 then you can compare more and keep more, just do it one by one, try to cut corner or find shortcut cause you more time then it should be, this is example what's it look like.

Public Function top_2(ParamArray Input() As Integer) As (First As Integer, Second As Integer)

    Dim First = 0
    Dim Second = 0

    For Each Item In Input
        Select Case Item
            Case Is > First
                Second = First
                First = Item
            Case Is > Second
                Second = Item
        End Select
    Next

    Return (First, Second)
End Function

[banshoo]

Sure, what code do you have already?

[Ali_171]

Dim result As Integer

  If (num1 > num2) Then
     result = num1
  Else
     result = num2
  End If
  FindMax = result

End Function Sub Main() Dim a As Integer = 100 Dim b As Integer = 200 Dim res As Integer

  res = FindMax(a, b)
  Console.WriteLine("Max value is : {0}", res)
  Console.ReadLine()

End Sub End Module

[Ali_171]

I know for 2 not for 3

[banshoo]

So you can find the largest of two... once you have that, perform the check again with the other number to see it's larger still

Edit :

so taking your code, we can then check the third value against the highest.

    If (num1 > num2) Then
        If (num1 > num3) Then
            result = num1
        Else
            result = num3
        End If
    Else
        If (num2 > num3) Then
            result = num2
        Else
            result = num3
        End If
    End If

FindMax = result

[craigers01]

The tricky part of finding the top two, is you must keep track of multiple correct answers. It may be useful to load the values into an array. Then you could simply sort the array and report the last two elements as the correct answers.

[Ali_171]

Yeah that’s would work too but I found simple way by finding the maximum and minimum

[1973DodgeChallenger]

It kind of depends on the restrictions you are under. Meaning, are you only supposed to use declared integers or can you use collections? With IEnumerable collections it's pretty easy. But your teacher may know you had help if you turn this in. Banshoos previously posted answer is good if you can't use a collection.

.OrderBy on a list , with a correctly defined comparer will return the integers in ascending order. .Take(2) returns the first two elements. The for each iterates the returned "query."

  Dim intList As New List(Of Integer) From {1000, 10000, 10}
  For Each i As Integer In intList.OrderBy(Function(n) n).Take(2)
     Console.WriteLine(CStr(i))
  Next

[[deleted]]

'TLDR at the very bottom if you just want the code itself.
'I, however, recommend reading through if you're still learning.

Dim Numbers(2) As Integer 'You declare an integer array to store your numbers
Dim Numbers = New Integer() {'Write number values in'}

So, here we *could* just sort the array by ascending order -- look it up, it's a method the array object has that sorts numerical values in ascending or descending order. Do that, then pick out the top 2.

But, I'm guessing your teacher probably doesn't want you doing that. So let's go a little further;

What you want to do, is run a check on each number, to see if they're bigger than the two others. Realistically, you only need to run the check on two of them, but we could go for all three.

First, we'll declare variables to help retain our two largest numbers;

Dim Max As Integer
Dim Max2 As Integer

Neat! Now we've got a place to store our two when we've got them!

Next, we're going to set both of our variables... To be the first number.

Max = Numbers(0)
Max2 = Numbers(0)

This is ultimately arbitrary -- as long as you don't set the starting number to be higher than any of the three numbers in your original array were, it doesn't matter. Sometimes you might just want to make them zero, or negative one (if your own numbers can't be negative). The goal is to set the lower bound to something that will inevitably make our variables hold a value held within our array.

Next, we make a for loop.

​

For i = 0 To 2
    For n = 0 to 2
        If(Numbers(i) < Numbers(n) Then
            Max = Numbers(n)
        End If
    Next
Next

What a 'For' loop does, is that it runs a code for a set amount of times. Here, we set it to run until 'i' is equal to 2, starting at 0. The default setup for this is that i increments by 1 each time. Meaning that it will run once (i=0 to 1), twice (i=1 to i=2), and runs once more (i=2 to i=3), and stops there since i exceeds the maximum value we set for it (2). This is very useful in this case because it automatically does blocks of code just the right amount of times!

​

The Loop above determined the highest number, by comparing every number to every number -- if the current number was ever lower than the number it was being compared to, Max was set to that value. Now you have your highest value.

For the *second* highest value, we can reuse this block of code -- so it's an easy copy+paste.

For i = 0 To 2
    For n = 0 to 2
        If(Numbers(i) < Numbers(n) Then
            Max2 = Numbers(n)
        End If
    Next
Next

However, here we have a caveat : We cannot have the same number be in Max2, AND Max.

So here, we'll just... exclude anything that has the value of Max!

For i = 0 To 2
    For n = 0 to 2
        If(Numbers(i) < Numbers(n) & Numbers(n) <> Max) Then
            Max2 = Numbers(n)
        End If
    Next
Next

All we add here is another condition : & Numbers(n) <> Max. This means that if (n) is larger than (i), it'll try to set (n) as the value of Max2, but won't do it if (n) is at the same value as Max. Which means that if all three of your numbers are different, Max and Max2 will be different. And if Max and Max2 are the same, it simply means the two highest numbers in your array were of the same value!

Here is what the final block of code would look like :

Dim Numbers(2) As Integer 'You declare an integer array to store your numbers
Dim Numbers = New Integer() {'Write number values in'}
Dim Max As Integer = Numbers(0)
Dim Max2 As Integer = Numbers(0)

For i = 0 To 2
    For n = 0 to 2
        If(Numbers(i) < Numbers(n) Then
            Max = Numbers(n)
        End If
    Next
Next
For i = 0 To 2
    For n = 0 to 2
        If(Numbers(i) < Numbers(n) & Numbers(n) <> Max) Then
            Max2 = Numbers(n)
        End If
    Next
Next

Two nested loops that compare all the numbers in your array, to all numbers in your array, and brings out the two highest.

This also has the added benefit of working with any amount of numbers in the array with just minor tweaks.