Math with letters

[Travis]

I have a question about how to get this to work:

I have the following:

Const A As Integer = 0
Const B As Integer = 1
Const C As Integer = 2
etc...

I have a textbox (txtInput) that people can type in. Say they type in "AB"
and hit the button to calculate. I want it to be able to take the string
(strText) (which contains the letters AB) and convert that text into a form
where it recognizes the letters as constants and not a string. AB = 0 (0*1),
but I can't get there because it only sees the text "AB." Its like writing
"class" and class. The first is a string, the other is a keyword. How do I
take the string and get it to see that it's a bunch of constants, not a
string?

Do you get what I'm trying to ask? If they enter in ABC it to do the math of
0*1*2 and output that, not output the text ABC again.

There must be a simple way of doing this that I'm not thinking of?

Thanks!

[PJ6]

Re: Math with letters

The functions below will do what you want, but you may want to consider
doing something like this instead -

Public Shared Readonly A As New KeyValuePair(Of String, Integer)("A", 0)
Public Shared Readonly B As New KeyValuePair(Of String, Integer)("B", 1)
Public Shared Readonly C As New KeyValuePair(Of String, Integer)("C", 2)

Paul

-----
(Imports System.Reflecti on)

Public Shared Function GetFieldValue(O f ReturnType)(ByV al Type As Type,
ByVal FieldName As String) As ReturnType
Dim ret As ReturnType = Nothing
Dim b As BindingFlags = BindingFlags.No nPublic Or BindingFlags.Pu blic Or
BindingFlags.St atic
Dim fi As FieldInfo = Type.GetField(F ieldName, b)
If fi Is Nothing Then Throw New ArgumentExcepti on(String.Forma t("{0} not
found on type", FieldName))
If Not fi.FieldType Is GetType(ReturnT ype) Then Throw New
ArgumentExcepti on(String.Forma t("{0} is not of type {1}", FieldName,
GetType(ReturnT ype).Name))
Dim val As Object = fi.GetValue(Not hing)
If Not val Is Nothing Then ret = DirectCast(val, ReturnType)
Return ret
End Function

Public Shared Function GetFieldValue(O f ReturnType)(ByV al o As Object,
ByVal FieldName As String) As ReturnType
Dim ret As ReturnType = Nothing
Dim b As BindingFlags = BindingFlags.No nPublic Or BindingFlags.Pu blic Or
BindingFlags.St atic Or BindingFlags.In stance
Dim fi As FieldInfo = o.GetType.GetFi eld(FieldName, b)
If fi Is Nothing Then Throw New ArgumentExcepti on(String.Forma t("{0} not
found on type", FieldName))
If Not fi.FieldType Is GetType(ReturnT ype) Then Throw New
ArgumentExcepti on(String.Forma t("{0} is not of type {1}", FieldName,
GetType(ReturnT ype).Name))
Dim val As Object = fi.GetValue(o)
If Not val Is Nothing Then ret = DirectCast(val, ReturnType)
Return ret
End Function


"Travis" <captaint03@com cast.netwrote in message
news:%23CwdcksN JHA.728@TK2MSFT NGP06.phx.gbl.. .

>I have a question about how to get this to work:
>
I have the following:
>
Const A As Integer = 0
Const B As Integer = 1
Const C As Integer = 2
etc...
>
I have a textbox (txtInput) that people can type in. Say they type in "AB"
and hit the button to calculate. I want it to be able to take the string
(strText) (which contains the letters AB) and convert that text into a
form where it recognizes the letters as constants and not a string. AB = 0
(0*1), but I can't get there because it only sees the text "AB." Its like
writing "class" and class. The first is a string, the other is a keyword.
How do I take the string and get it to see that it's a bunch of constants,
not a string?
>
Do you get what I'm trying to ask? If they enter in ABC it to do the math
of 0*1*2 and output that, not output the text ABC again.
>
There must be a simple way of doing this that I'm not thinking of?
>
Thanks!

[Jack Jackson]

Re: Math with letters

On Sat, 25 Oct 2008 13:42:46 -0400, "Travis" <captaint03@com cast.net>
wrote:

>I have a question about how to get this to work:
>
>I have the following:
>
>Const A As Integer = 0
>Const B As Integer = 1
>Const C As Integer = 2
>etc...
>
>I have a textbox (txtInput) that people can type in. Say they type in "AB"
>and hit the button to calculate. I want it to be able to take the string
>(strText) (which contains the letters AB) and convert that text into a form
>where it recognizes the letters as constants and not a string. AB = 0 (0*1),
>but I can't get there because it only sees the text "AB." Its like writing
>"class" and class. The first is a string, the other is a keyword. How do I
>take the string and get it to see that it's a bunch of constants, not a
>string?
>
>Do you get what I'm trying to ask? If they enter in ABC it to do the math of
>0*1*2 and output that, not output the text ABC again.
>
>There must be a simple way of doing this that I'm not thinking of?
>
>Thanks!

If the text letters are only A - Z and have the values 0 - 25, you can
convert the text to an integer:

Dim xx As String = "ABC"
Dim rslt As Integer = 0

For Each chr As Char In xx.ToUpper().To CharArray()
rslt *= Asc(chr) - Asc("A"c)
Next

You would also need to add checking for invalid characters.

If the set of legal characters includes other characters, or if the
values do not map linearly with the letters, you might want to build a
table of legal values:

Dim dict as New Dictionary(Of Char, Integer)

With dict
.Add("A"c, 0)
.Add("B"c, 1)
...
.Add("%"c, 99)
End With

For Each chr As Char In xx.ToUpper().To CharArray()
If dict.ContainsKe y(chr)
rslt *= dict(chr)
Else
' Invalid character
Next

[James Hahn]

Re: Math with letters

Is there any reason to use variable names to find the required values to be
multiplied?

If the association of values to letters is arbitrary (for instance, not
based on the letter's ASCII code) the following example shows one way that
it can be done without using variable names:
Public Class Form1

Dim myLabels() As Char = {"A"c, "B"c, "C"c, "D"c, "E"c, "F"c} 'etc.

Dim myValues() As Integer = {0, 1, 2, 3, 4, 5} 'etc.

Private Sub Button1_Click(B yVal sender As System.Object, ByVal e As
System.EventArg s) Handles Button1.Click

Dim a() = TextBox1.Text.T oCharArray

Dim result As Integer = 1

For Each c In a

result = result * myValues(Array. IndexOf(myLabel s, c))

Next

textbox2.text = result.ToString

End Sub


"Travis" <captaint03@com cast.netwrote in message
news:%23CwdcksN JHA.728@TK2MSFT NGP06.phx.gbl.. .

>I have a question about how to get this to work:
>
I have the following:
>
Const A As Integer = 0
Const B As Integer = 1
Const C As Integer = 2
etc...
>
I have a textbox (txtInput) that people can type in. Say they type in "AB"
and hit the button to calculate. I want it to be able to take the string
(strText) (which contains the letters AB) and convert that text into a
form where it recognizes the letters as constants and not a string. AB = 0
(0*1), but I can't get there because it only sees the text "AB." Its like
writing "class" and class. The first is a string, the other is a keyword.
How do I take the string and get it to see that it's a bunch of constants,
not a string?
>
Do you get what I'm trying to ask? If they enter in ABC it to do the math
of 0*1*2 and output that, not output the text ABC again.
>
There must be a simple way of doing this that I'm not thinking of?
>
Thanks!