Is there a C# equivalent of the VB.NET asc function?

[Alan Silver]

Hello,

I'm converting some old VB6 code to use with ASP.NET and have come
unstuck with the Asc() function. This was used in the old VB6 code to
convert a character to its ASCII numeric equivalent.

Is there such a function available in C#? I can see that VB.NET has one,
but I couldn't see how to get at it in C#.

For example, if I have ...

string str = "Hello";

.... how would I do the following (where I have used the VB Asc()
function in my C# pseudocode)...

int sum = 0;
for (int i=0; i:str.Length(); i++) {
sum += Asc(str.Substring(i,1));
}

TIA

 

[Brock Allen]

I'm converting some old VB6 code to use with ASP.NET and have come

unstuck with the Asc() function. This was used in the old VB6 code to
convert a character to its ASCII numeric equivalent.

Is there such a function available in C#? I can see that VB.NET has
one, but I couldn't see how to get at it in C#.

char c = 'A';
int val = (int)x;

 

[Steve C. Orr [MVP, MCSD]]

Will this work?
x = System.Convert.ToInt32(Mychar.Substring(0, 1));

 

[Guest]

Give this a shot

sum += (int) str;

Jim

 

[Alan Silver]

I'm converting some old VB6 code to use with ASP.NET and have come

char c = 'A';
int val = (int)x;

Oh, isn't that clever!!

Can I convert back as easily? I mean the equivalent of the Chr()
function? I'm sure it's probably as simple as another cast, but my brain
isn't clear enough (1am after a really lousy day's work) to be sure I'm
doing it right!!

Also (whilst you're being so helpful), is there an equivalent of the Xor
operator? I was using this for some encryption, but couldn't work out
how to do it in C#. The .NET class library is so big that it's hard to
find your way around.

Thanks very much for the help. Any further help would be greatly
appreciated.

 

[Alan Silver]

Give this a shot

sum += (int) str;

Ooh-err, another useful tip. I'd forgotten that you can treat strings
like char arrays. That will make life easier.

Thanks for the tip. Please read my other reply and see if you can shed
any light on the Xor question.

Thanks again

 

[Guest]

Yes,

' ' == (char) 20

and you want ^
eg 11110000 ^ 10101010 equals 01011010

Sombody's in the UK writing some sort of license key/password hashing
algorithm??!

Jim

 

[Alan Silver]

Yes,

' ' == (char) 20

and you want ^
eg 11110000 ^ 10101010 equals 01011010

Thanks!! I love the simplicity of C#. I just need to get it all in my
head.

It occurred to me in bed last night that the C# equivalent of Xor was
probably an operator, not a method of a class. That explains why I
couldn't find it in the class library. Ho hum.

Sombody's in the UK writing some sort of license key/password hashing
algorithm??!

Not quite that fancy, but close. I have an old VB6/ASP application that
encrypts some sensitive data before storing it in the database. I'm
trying to rewrite it bit by bit in ASP.NET and am trying to convert the
encryption/decryption routines as accurately as possible.

To be honest, the code is quite old and not my best!! I would really
like to re-engineer the whole thing from scratch, but there's too much
legacy data around to allow that at the moment. I need to get the new
system working with the old data as quickly as possible. I have the
following inelegant and inefficient function ...

Public Function Encode(Key As String, ByVal Str As String) As String
Dim Tmp As String, RealKey As String, sc As String, kc As String
Dim l As Integer, i As Integer
Tmp = StrReverse(Key) ' save the key passed to us
RealKey = ""
l = Len(Tmp & Main.RealSeed)
For i = 1 To l ' build up the full key from the seed and the passed
key
RealKey = RealKey & Mid(Tmp, i, 1) & Mid(Main.RealSeed, i, 1)
Next
Tmp = "" ' will hold the encoded string
For i = 1 To Len(Str)
sc = Asc(Mid(Str, i, 1))
kc = Asc(Mid(RealKey, i, 1))
Tmp = Tmp & Chr(sc Xor kc)
Next
Encode = Tmp
End Function

.... which I am trying to rewrite in C#. As you can see, the code is not
something to be proud of!! I wrote it a long time ago and have learned a
lot since then.

By the way, if you're trying to make sense of it, Main.RealSeed refers
to a variable in the Main from of the application that holds a seed for
the (admittedly basic) encryption routine.

Thanks for the help.

 

[Guest]

If you're not having fun doing it (and actually a better reason...) you
probably shouldn't be doing this yourself, as it's weak, and .NET already has
all this stuff done for you.

If it's one way hashing you need (like checking passwords) use MD5
System.Security.Cryptography.MD5

which is pretty easy
byte[] data = new byte[DATA_SIZE];

// This is one implementation of the abstract class MD5.
MD5 md5 = new MD5CryptoServiceProvider();

byte[] result = md5.ComputeHash(data);


If you need proper 2 way encryption use something like RSA
System.Security.Cryptography.RSACryptoServiceProvider

admittedly it's not quite trivial, but the docs are good and there's tons of
examples out there. Plus you wont get screwed if someone decyphers your
"encoding" (it's not really encryption is it, its just encoding).

ms-help://MS.VSCC.2003/MS.MSDNQTR.2003FEB.1033/cpguide/html/cpconcryptographyoverview.htm

I'm by no means an encryption expert so I can't recommend an encryption
scheme to use, but I would certainly suggest looking at this.

Jim

 

[Alan Silver]

Jim,

Thanks for the reply...

If you're not having fun doing it (and actually a better reason...) you
probably shouldn't be doing this yourself, as it's weak, and .NET already has
all this stuff done for you.

I'm not having a bad time doing it, I'm just a bit pushed for time and
would prefer to have more chance to learn all this properly.

As far as the .NET framework's offerings, I would love to use them and
do the job properly, but as explained, I'm working with a lot of legacy
data that has been encrypted using the existing method. I need to make
sure the new system can read the old data.

At some point (when I ever get enough time, ha ha ha) I would like to
rewrite this system from scratch. At that point, I would use whatever
..NET has to offer as it's bound to be more stable and easier than
writing my own code. Unfortunately, I don't see that happening in the
near future ;-(

Thanks again for the reply. The info is useful anyway.

If it's one way hashing you need (like checking passwords) use MD5
System.Security.Cryptography.MD5

which is pretty easy
byte[] data = new byte[DATA_SIZE];

// This is one implementation of the abstract class MD5.
MD5 md5 = new MD5CryptoServiceProvider();

byte[] result = md5.ComputeHash(data);


If you need proper 2 way encryption use something like RSA
System.Security.Cryptography.RSACryptoServiceProvider

admittedly it's not quite trivial, but the docs are good and there's tons of
examples out there. Plus you wont get screwed if someone decyphers your
"encoding" (it's not really encryption is it, its just encoding).

ms-help://MS.VSCC.2003/MS.MSDNQTR.2003FEB.1033/cpguide/html/cpconcryptog
raphyoverview.htm

I'm by no means an encryption expert so I can't recommend an encryption
scheme to use, but I would certainly suggest looking at this.

Jim