Nested For Loop to populate matrix

[Killer42]

The original question asked for nested loops. Post #4 showed you're getting the idea. One technique which would work is to have the outer loop (let's say X) step by 5 at a time, and have the inner Y loop go from X to X + 4.

It's important that you learn to understand and be comfortable with loops, including nested loops. They're a very important and heavily-used feature of the language.

jamesd0142, I'd like to make two points. First, using an array seems somewhat over the top for such a simple task. And second, please remember that we don't hand out answers to homework questions (though helping to understand the problem is fine). Oh, and a third point I just thought of. What purpose does your array serve? How is using hold(i) any different to using i?

Oh, and werks... I'm watching you too... ;)

[Killer42]

... Form and Design are nowhere to be found ... I know this is simple for some but man this program is frustrating lol

From what I've heard, while there are undoubtedly improvements in the later versions, VB6 is much quicker and simpler to work with. It's a shame M$ had to make such a radical change of direction. :(

The crazy thing is that schools all over the place are still teaching VB6, which is now well over ten years old and at least 3 or 4 versions behind the times.

[slvr02scooby]

Ok this is where i'm at now:

Dim A As Integer
    Dim B As Integer = 0
    Dim g_str As String = "The matrix is:" & vbNewLine
    Private Sub Button1_Click(ByVal sender As System.Object, _
    ByVal e As System.EventArgs) Handles Button1.Click
        Dim B As Integer = 0
        For A = 0 To 49
            For B = 0 To 4
                g_str &= " 0 "
            Next
            For B = 0 To 49
                A += 1
            Next
            g_str &= vbNewLine
        Next
        MsgBox(g_str)
    End Sub
End Class

I know line 9 is wrong, right now I get the output of "0 0 0 0 0" So I have the 5 numbers on one line, but I can't figure out the formula I need to put in what I believe goes on line 9... Do I need to add another farther down?

[Killer42]

I'd suggest the following...

• On line 9, simply use B.
• On line 8, don't count from 0 to 4. Count from A to A + 4.
• Remove lines 11-13, look up the STEP clause of the FOR statement, and fix line 7.

By the way, you need to decide on the scope of your variables. You've got some defined at the form level, and B also defined locally in the Sub. The definitions are a bit inconsistent, too. Why are you initialising B to 0, but not A?

[jamesd0142]

vb2005 stores the project files in:

My Documents > Visual Studio 2005 > Projects

and to display it in a msg make changes like this:

[code=vbnet]
Public Class Form1
Dim i As Integer
Dim a As Integer = 0
Dim hold(49) As Integer

Dim output As String 'new line

Private Sub Button1_Click(B yVal sender As System.Object, ByVal e As System.EventArg s) Handles Button1.Click
Dim a As Integer = 0
For i = 0 To 49
hold(i) = i
Next
For i = 0 To 49
a += 1
output = output & hold(i) & " " 'chenges
If a = 5 Then
output = output & vbCrLf ' changes
a = 0
End If
Next
MsgBox(Mid(outp ut, 1, Len(output) - 2)) 'changes
End Sub
End Class

[/code]

[jamesd0142]

jamesd0142, I'd like to make two points. First, using an array seems somewhat over the top for such a simple task. And second, please remember that we don't hand out answers to homework questions (though helping to understand the problem is fine). Oh, and a third point I just thought of. What purpose does your array serve? How is using hold(i) any different to using i?

ok so i gave this a go also without the array, which i agree was a waste of time :P

anyways my question is why do you need to use nested for loops when this simple code below works?
[code=vbnet]
Dim i As Integer
Dim j As Integer = 0
For i = 0 To 49
j = j + 1
If j = 6 Then
j = 1
TextBox1.Text = TextBox1.Text & vbCrLf
TextBox1.Text = TextBox1.Text & i & " "
Else
If i = 49 Then
TextBox1.Text = TextBox1.Text & i
Else
TextBox1.Text = TextBox1.Text & i & " "
End If
End If
Next
[/code]

[Killer42]

... anyways my question is why do you need to use nested for loops when this simple code below works?

Though it doesn't actually specify nesting, the original post says...

we're required to use two For Statements

[jamesd0142]

Though it doesn't actually specify nesting, the original post says...

ah i see. it kind of gave me a head ache yesterday trying for bout an hour to work out how to do it with two for loops.

:S

[slvr02scooby]

It still is giving me a headache...

[Killer42]

It still is giving me a headache...

Did you try taking the code from post #18 and making the changes I suggested in #19?

We're trying to help you understand how to go about it, but we're not allowed to just hand you the answer.

[jamesd0142]

Do you use the debug tool to step through your program?

This is a vital step when learning to use VB as it shows you exactly what your code is doing.

[slvr02scooby]

Yes thank you for the tips killer, i've made the changes, but at this point it just displays "0" and in fact freezes once it's running, have to use task manager to close it.

This is what I have now:

Dim A As Integer
    Dim B As Integer
    Dim g_str As String = ""
    Private Sub Button1_Click(ByVal sender As System.Object, _
    ByVal e As System.EventArgs) Handles Button1.Click
        For A = 0 To 49
            If A < 10 Then
                g_str &= A & "   "
            Else
                g_str &= A & " "
            End If
            If A Mod 10 = 0 Then
                g_str &= vbNewLine
            End If
            For B = 0 To 4
            Next
            g_str &= vbNewLine
        Next
        MsgBox(g_str)
    End Sub
End Class

I tried to integrate some of the lessons we learned last class but now it just freezes so i've only gone down hill... What I don't understand is this code that we did in class will display 1 through 100, but how do I put in another For statement and obviously change the numbers to 0 through 49?

Dim s As String = ""
    Dim i As Integer
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        For i = 1 To 100
            If i < 10 Then
                s &= i & "   "
            Else
                s &= i & " "
            End If
            If i Mod 10 = 0 Then
                s &= vbNewLine
            End If
        Next
        MsgBox(s)
        s = ""
    End Sub
End Class

Of course now i'm on time crunch and need to get this in by tomorrow (tuesday) by 6pm (pst)

[QVeen72]

Hi,

Is this what you are looking for :

[code=vb]
Private Sub Command1_Click( )
Dim i As Integer
Dim s As String
Dim k As Integer
Dim j As Integer
s = ""
k = 0
i = -1
j = 0
Do
i = i + 1
s = s & Space(3 - Len(CStr(i))) & CStr(i)
k = k + 1
If k >= 5 Then
j = j + 1
s = s & vbCrLf
k = 0
If j >= 10 Then Exit Do
End If
Loop
MsgBox s
End Sub
[/code]

My code is for VB6 just change vbCrLF to vbNewLine in above code, it should work for VB.net also..


Regards
Veena

[slvr02scooby]

I appreciate the help but that is far too advanced for what i'm doing lol, I just need to use 2 for statements

[QVeen72]

Hi,

How about this :

[code=vb]
Private Sub Command1_Click( )
Dim i As Integer
Dim s As String
Dim k As Integer
Dim j As Integer
s = ""
k = -1
For i = 1 To 10
For j = 1 To 5
k = k + 1
s = s & " " & CStr(k)
Next
s = s & vbCrLf
Next
MsgBox s
End Sub

[/code]

REgards
Veena