CODEWITHSUNDEEP
vb.netfunction
Daniel Gmail
Daniel Gmail

Reputation: 11

Is this code the right code for this task?

Create a function called swapped that will take two integers(a,b) called byref and return a Boolean that is true if the numbers have been swapped. Within the routine compare the numbers and if b>a swap them using a local variable temp, then return the value true else return the value false.

Function swapped(ByRef a As Boolean, ByRef b As Boolean)
    a = True
    b = True
    If b > a Then
        temp = b
        b = a
        a = temp
        a = True
        b = True
    Else
        a = False
        b = False
    End If

Upvotes: 0

Views: 80

Answers (3)

djv
djv

Reputation: 15774

Both existing answers do the trick. Here is one without a temp variable

Private Function swapped(ByRef a As Integer, ByRef b As Integer) As Boolean
    If b > a Then
        a = a + b
        b = a - b
        a = a - b
        Return True
    End If
    Return False
End Function

Sub Main()
    Dim a = 10
    Dim b = 11
    Console.WriteLine($"a: {a}, b: {b}")
    Console.WriteLine($"values were{If(swapped(a, b), " ", " not ")}swapped.")
    Console.WriteLine($"a: {a}, b: {b}")
    Console.ReadLine()
End Sub

Upvotes: 0

DjJazzyJeffTN
DjJazzyJeffTN

Reputation: 86

Here is a fixed example. You should have the parameters declared as integers instead of boolean. The function itself should be declared as a boolean

Function swapped(ByRef a As Integer, ByRef b As Integer) As Boolean

    If b > a Then
       'Declare the temp variable
        Dim temp As Integer = b

       'Change b to a
        b = a
       'Set 'a' equal to the temp variable from the original b
        a = temp

        Return True

    Else
        Return False

    End If
End Function

Public Sub test()
    Dim intA As Integer
    Dim intB As Integer
    intA = 1
    intB = 2
    'Test b>a
    'Should return True
    Dim check As Boolean
    check = swapped(intA, intB)

    'Test Not(b>a)
    'Should return False
    Dim checkfalse As Boolean
    checkfalse = swapped(2, 2)
End Sub

Upvotes: 1

Mary
Mary

Reputation: 15091

First let's look at your code.

'The requirements called for 2 Integers, not Booleans.
'A Function requires a datatype, in this can a Boolean
Private Function swapped(ByRef a As Boolean, ByRef b As Boolean)
    'Assigning values here will overwrite the passed in values
    a = True
    b = True
    'What would it mean for True > True ??
    If b > a Then
        'temp isn't declared so this will not compile
        temp = b
        'here I think you are trying to do the swap
        'but all the values are True
        b = a
        a = temp
        a = True
        b = True
    Else
        a = False
        b = False

    End If
    'Function need a return value to match the datatype of the function
    'It is preceded by Return
End Function

If you are working in Visual Studio (free for the download), several of these errors will be highlighted for you.

Now, let's look at some code that may accomplish your task.

'Through comments you have already figured out that a and b are Integers
'In addition, Functions always need a return type. In this case a Boolean
    Function swapped(ByRef a As Integer, ByRef b As Integer) As Boolean
    'The values of a and b are passed to the function.
    'Keep the passed in value of a in a new variable
    If b > a Then
        Dim aPassedInValue = a
        'assign the value of b to a
        a = b
        'now assign the original value of a to b
        'we can't use a because we just changed the value of a in the above line
        b = aPassedInValue
        'There have been no errors so we can return True
        Return True
    Else 'We didn't swap them
        Return False
    End If
End Function

Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
    Dim c As Integer = 7
    Dim d As Integer = 20
    MessageBox.Show($"c = {c}, d = {d}", "Before Swap")
    Dim ReturnValue = swapped(c, d)
    MessageBox.Show($"The return value of the swapped Function is {ReturnValue}")
    MessageBox.Show($"c = {c}, d = {d}", "After Swap")
End Sub

I think the point of this exercise is to demonstrate ByRef. You have changed the values in the function and the new values are reflected in the variable in the Button.Click Sub.

Upvotes: 1

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