[RESOLVED] Problem with Asc()

[Poppa Mintin]

Hi,

I have a little tool which I use to read the ASCII value of individual characters in a string. The form includes a TextBox and a Button.
I enter a word to check into TextBox1, and click Button2 to read the ASCII value of each successive character in turn.

Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
        Static a As Integer = 0
        If a = TextBox1.TextLength - 1 Then Label1.Text = "Ok." : Exit Sub
        Dim z As Char = CChar(TextBox1.Text.Substring(a, 1))
        Dim b As Integer = Asc(z)
        Dim y As String = Chr(b)
        Label1.Text = b.ToString
        a += 1
        End Sub

Entering the string Рахів and running the tool with a breakpoint at Line 9, the results I get are: -

z = "Р"c Char: b = 63 Integer: y = "?" String
z = "а"c Char: b = 63 Integer: y = "?" String
z = "х"c Char: b = 63 Integer: y = "?" String
z = "і"c Char: b = 63 Integer: y = "?" String
z = vbNullChar Char: b = 0 Integer: y = Nothing String

I don't understand these results.


Poppa

[Niya]

I'm going to give you the best piece of advice you've ever gotten, please for the love of God and everything sacred in this life stop using ASCII. ASCII is a dinosaur that the world has forgotten about. It is the steam engine of String formats. Modern Strings are Unicode Strings, not ASCII. ASCII code in the modern age only appear to work correctly until they encounter Strings that use characters that cannot map cleanly to ASCII/ANSI codes.

Right now I'm in the middle of doing an exam so I can't go into details like I usually do with code snippets and deep explanations but I'm sure there are other members here that can help you formulate a better way to do what you're doing. The primary problem with your code just from looking at it is that it doesn't treat Strings like a collection of 2 byte Unicode encoded characters which it should be doing. I'm not surprised you're running into problems.

[PlausiblyDamp]

Hi,

I have a little tool which I use to read the ASCII value of individual characters in a string. The form includes a TextBox and a Button.
I enter a word to check into TextBox1, and click Button2 to read the ASCII value of each successive character in turn.

Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
        Static a As Integer = 0
        If a = TextBox1.TextLength - 1 Then Label1.Text = "Ok." : Exit Sub
        Dim z As Char = CChar(TextBox1.Text.Substring(a, 1))
        Dim b As Integer = Asc(z)
        Dim y As String = Chr(b)
        Label1.Text = b.ToString
        a += 1
        End Sub

Entering the string Рахів and running the tool with a breakpoint at Line 9, the results I get are: -

z = "Р"c Char: b = 63 Integer: y = "?" String
z = "а"c Char: b = 63 Integer: y = "?" String
z = "х"c Char: b = 63 Integer: y = "?" String
z = "і"c Char: b = 63 Integer: y = "?" String
z = vbNullChar Char: b = 0 Integer: y = Nothing String

I don't understand these results.


Poppa

I completely agree with Niya's comments regarding Unicode and that really is the correct way to handle strings.

However, I am unclear on what you are trying to do with these lines of code

Dim z As Char = CChar(TextBox1.Text.Substring(a, 1))
Dim b As Integer = Asc(z)
Dim y As String = Chr(b)

If z is a Char, what do you expect turning it into it's ASCII code and then turning it back into a Char will do? Ideally it will just return the same character as is stored in the variable z, however this will fail if the character isn't an ASCII character, if codepage translations aren't reversible, or might even throw an exception if the Asc() call can't actually map the character.

It might be more helpful if you explain what you are trying to achieve, what do you want the end result to be?

[jmcilhinney]

At the very least, use AscW and ChrW but don't do that either. Convert.ToInt32 will convert a Char to a Unicode value and Convert.ToChar will do the opposite. That's what you should be using, not those VB6 holdovers.

Also, this:

Dim z As Char = CChar(TextBox1.Text.Substring(a, 1))

can be replaced with this:

Dim z = TextBox1.Text(a)

[Poppa Mintin]

stop using ASCII[/I]. ASCII is a dinosaur that the world has forgotten about. It is the steam engine of String formats. Modern Strings are Unicode Strings, not ASCII. ASCII code in the modern age only appear to work correctly until they encounter Strings that use characters that cannot map cleanly to ASCII/ANSI codes.

Thanks for the advice Niya... However, that's far far easier said than done. I can't find anything anywhere which explains how to amend my code to accomplish the task. It certainly doesn't help when (Despite having VB selected) the examples are in C# !

We dinosaurs tend to use dinosaur code.


Poppa

[dbasnett]

What you were told

    Private txt1IDX As Integer = 0
    Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
        If txt1IDX >= TextBox1.TextLength Then
            txt1IDX = 0
            Label1.Text = "Ok."
            Exit Sub
        End If
        Dim b As Integer = Convert.ToUInt32(TextBox1.Text(txt1IDX))
        Label1.Text = b.ToString
        txt1IDX += 1
    End Sub

    Private Sub TextBox1_TextChanged(sender As Object, e As EventArgs) Handles TextBox1.TextChanged
        txt1IDX = 0
    End Sub

[PlausiblyDamp]

Thanks for the advice Niya... However, that's far far easier said than done. I can't find anything anywhere which explains how to amend my code to accomplish the task. It certainly doesn't help when (Despite having VB selected) the examples are in C# !

We dinosaurs tend to use dinosaur code.


Poppa

If the examples are in C# then they might be even easier to convert than trying to use legacy VB6 methods. What C# snippets are you trying to convert?

[Poppa Mintin]

If the examples are in C# then they might be even easier to convert than trying to use legacy VB6 methods. What C# snippets are you trying to convert?

Hi PlausiblyDamp,

I wasn't trying to convert 'em, I was just complaining that examples in a vb.NET text were in C#.

Pop.

[Poppa Mintin]

Thanks all,

I am often accused of using VB6 code... I have Never used VB6 for anything...
This dinosaur still thinks in terms of VB3.0.

Thanks again to John, always useful advice.

Poppa