VB.NET Random / C++ rnd - Visual Basic .NET

Nick

Hi there,

I'm trying to create a random number via a seed in VB.NET and C++, 2
different applications. I want to be able to use the same seed and get the
same random number but unfortunately VB.NET's Random class produces a
different set of results than the C++ rnd function.

I can't see any reference of rnd being used via API declarations and am just
trying to find a way of generating a random number via seed that is
identical in both languages. Of course I could create a C++ DLL to do it
for me and use it in the VB app, but i'd rather not go to that extreme for 1
method.

Any suggestions would be greatly appreciated!

Nick.

Aug 6 '08 #1

Subscribe Reply

3650

Michael D. Ober

"Nick" <a@a.comwrote in message
news:%2******** ********@TK2MSF TNGP05.phx.gbl. ..

Hi there,

I'm trying to create a random number via a seed in VB.NET and C++, 2
different applications. I want to be able to use the same seed and get
the same random number but unfortunately VB.NET's Random class produces a
different set of results than the C++ rnd function.

I can't see any reference of rnd being used via API declarations and am
just trying to find a way of generating a random number via seed that is
identical in both languages. Of course I could create a C++ DLL to do it
for me and use it in the VB app, but i'd rather not go to that extreme for
1 method.

Any suggestions would be greatly appreciated!

Nick.

If you are using managed C++ (C++/CLI), you can use the Random class in both
VB.Net and C++.

Mike.

Aug 6 '08 #2

Gillard

be happy to have a different set of result :

if not why would it be called random ?

"Michael D. Ober" <obermd.@.alum. mit.edu.nospam. wrote in message
news:Ja******** *************** *******@earthli nk.com...

"Nick" <a@a.comwrote in message
news:%2******** ********@TK2MSF TNGP05.phx.gbl. ..
>Hi there,

I'm trying to create a random number via a seed in VB.NET and C++, 2
different applications. I want to be able to use the same seed and get
the same random number but unfortunately VB.NET's Random class produces a
different set of results than the C++ rnd function.

I can't see any reference of rnd being used via API declarations and am
just trying to find a way of generating a random number via seed that is
identical in both languages. Of course I could create a C++ DLL to do it
for me and use it in the VB app, but i'd rather not go to that extreme
for 1 method.

Any suggestions would be greatly appreciated!

Nick.
If you are using managed C++ (C++/CLI), you can use the Random class in
both VB.Net and C++.

Mike.

Aug 6 '08 #3

Nick

Hi Mike,

It's not unfortunately, it's C++ / WTL, no managed code in sight
otherwise I wouldn't have this issue in the first place.

Nick.

"Michael D. Ober" <obermd.@.alum. mit.edu.nospam. wrote in message
news:Ja******** *************** *******@earthli nk.com...

"Nick" <a@a.comwrote in message
news:%2******** ********@TK2MSF TNGP05.phx.gbl. ..
>Hi there,

I'm trying to create a random number via a seed in VB.NET and C++, 2
different applications. I want to be able to use the same seed and get
the same random number but unfortunately VB.NET's Random class produces a
different set of results than the C++ rnd function.

I can't see any reference of rnd being used via API declarations and am
just trying to find a way of generating a random number via seed that is
identical in both languages. Of course I could create a C++ DLL to do it
for me and use it in the VB app, but i'd rather not go to that extreme
for 1 method.

Any suggestions would be greatly appreciated!

Nick.
If you are using managed C++ (C++/CLI), you can use the Random class in
both VB.Net and C++.

Mike.

Aug 6 '08 #4

Nick

Hi Gillard,

LOL! Unfortunately that's not quite how it works, otherwise there would
be no point in a random seed.

Nick.

"Gillard" <gillard_george s@@@@@@@@@hotma il.comwrote in message
news:%2******** ********@TK2MSF TNGP04.phx.gbl. ..

be happy to have a different set of result :

if not why would it be called random ?

"Michael D. Ober" <obermd.@.alum. mit.edu.nospam. wrote in message
news:Ja******** *************** *******@earthli nk.com...
>"Nick" <a@a.comwrote in message
news:%2******* *********@TK2MS FTNGP05.phx.gbl ...
>>Hi there,

I'm trying to create a random number via a seed in VB.NET and C++, 2
different applications. I want to be able to use the same seed and get
the same random number but unfortunately VB.NET's Random class produces
a different set of results than the C++ rnd function.

I can't see any reference of rnd being used via API declarations and am
just trying to find a way of generating a random number via seed that is
identical in both languages. Of course I could create a C++ DLL to do
it for me and use it in the VB app, but i'd rather not go to that
extreme for 1 method.

Any suggestions would be greatly appreciated!

Nick.
If you are using managed C++ (C++/CLI), you can use the Random class in
both VB.Net and C++.

Mike.

Aug 6 '08 #5

Mick Doherty

Does 'Microsoft.Visu alBasic.VBMath. Rnd' produce the same results as your C++
rnd() method?

--
Mick Doherty
http://www.dotnetrix.co.uk/nothing.html
"Nick" <a@a.comwrote in message
news:#j******** ******@TK2MSFTN GP05.phx.gbl...

Hi there,

I'm trying to create a random number via a seed in VB.NET and C++, 2
different applications. I want to be able to use the same seed and get
the same random number but unfortunately VB.NET's Random class produces a
different set of results than the C++ rnd function.

I can't see any reference of rnd being used via API declarations and am
just trying to find a way of generating a random number via seed that is
identical in both languages. Of course I could create a C++ DLL to do it
for me and use it in the VB app, but i'd rather not go to that extreme for
1 method.

Any suggestions would be greatly appreciated!

Nick.

Aug 6 '08 #6

Nick

Hi Mick,

Unfortunately not,

Microsoft.Visua lBasic.VBMath.R andomize(871)
Dim pIntAsciiCode As Integer
pIntAsciiCode = Rnd()

Result = 1, presumably due to rounding.

...

srand(871);
int pIntAsciiCode = 0;
pIntAsciiCode = rand();

Result = 2882

...

Hmm this isn't looking good really, a whole DLL to expose 1 method! :(
:( :(

Nick.
"Mick Doherty"
<EX***********@ AND.REMOVE.SQUA REBRACKETS.[mdaudi100#ntlwo rld.com]wrote in
message news:u1******** ******@TK2MSFTN GP05.phx.gbl...

Does 'Microsoft.Visu alBasic.VBMath. Rnd' produce the same results as your
C++ rnd() method?

--
Mick Doherty
http://www.dotnetrix.co.uk/nothing.html
"Nick" <a@a.comwrote in message
news:#j******** ******@TK2MSFTN GP05.phx.gbl...
>Hi there,

I'm trying to create a random number via a seed in VB.NET and C++, 2
different applications. I want to be able to use the same seed and get
the same random number but unfortunately VB.NET's Random class produces a
different set of results than the C++ rnd function.

I can't see any reference of rnd being used via API declarations and am
just trying to find a way of generating a random number via seed that is
identical in both languages. Of course I could create a C++ DLL to do it
for me and use it in the VB app, but i'd rather not go to that extreme
for 1 method.

Any suggestions would be greatly appreciated!

Nick.

Aug 6 '08 #7

Nick

I'm just looking at the Rnd method in Reflector and very different from the
C version unfortunately :(

"Mick Doherty"
<EX***********@ AND.REMOVE.SQUA REBRACKETS.[mdaudi100#ntlwo rld.com]wrote in
message news:u1******** ******@TK2MSFTN GP05.phx.gbl...

Does 'Microsoft.Visu alBasic.VBMath. Rnd' produce the same results as your
C++ rnd() method?

--
Mick Doherty
http://www.dotnetrix.co.uk/nothing.html
"Nick" <a@a.comwrote in message
news:#j******** ******@TK2MSFTN GP05.phx.gbl...
>Hi there,

I'm trying to create a random number via a seed in VB.NET and C++, 2
different applications. I want to be able to use the same seed and get
the same random number but unfortunately VB.NET's Random class produces a
different set of results than the C++ rnd function.

I can't see any reference of rnd being used via API declarations and am
just trying to find a way of generating a random number via seed that is
identical in both languages. Of course I could create a C++ DLL to do it
for me and use it in the VB app, but i'd rather not go to that extreme
for 1 method.

Any suggestions would be greatly appreciated!

Nick.

Aug 6 '08 #8

Nick

right, I've cracked and I now have a managed C++ class library which exposes
the C runtime methods.

"Mick Doherty"
<EX***********@ AND.REMOVE.SQUA REBRACKETS.[mdaudi100#ntlwo rld.com]wrote in
message news:u1******** ******@TK2MSFTN GP05.phx.gbl...

Does 'Microsoft.Visu alBasic.VBMath. Rnd' produce the same results as your
C++ rnd() method?

--
Mick Doherty
http://www.dotnetrix.co.uk/nothing.html
"Nick" <a@a.comwrote in message
news:#j******** ******@TK2MSFTN GP05.phx.gbl...
>Hi there,

I'm trying to create a random number via a seed in VB.NET and C++, 2
different applications. I want to be able to use the same seed and get
the same random number but unfortunately VB.NET's Random class produces a
different set of results than the C++ rnd function.

I can't see any reference of rnd being used via API declarations and am
just trying to find a way of generating a random number via seed that is
identical in both languages. Of course I could create a C++ DLL to do it
for me and use it in the VB app, but i'd rather not go to that extreme
for 1 method.

Any suggestions would be greatly appreciated!

Nick.

Aug 6 '08 #9

Feng Chen[MSFT]

Hello Nick,

Yes, use managed C++ can wrap the native functions in a library and use it
in .net applications. In addition, we can also import and directly call the
C runtime functions in the VB.net application using P/Invoke:

<DllImport
("msvcr80.dll", EntryPoint:="ra nd",CallingConv ention:=Calling Convention.Cdec l
)>
Public Shared Function rand() As Integer
End Function
<DllImport("msv cr80.dll", EntryPoint:="sr and", CallingConventi on:=
CallingConventi on.Cdecl)>
Public Shared Sub srand(ByVal _Seed As UInteger)
End Sub

Please let me know if you have any other concerns, or need anything else.

Best regards,
Feng Chen
Microsoft Online Community Support

Delighting our customers is our #1 priority. We welcome your comments and
suggestions about how we can improve the support we provide to you. Please
feel free to let my manager know what you think of the level of service
provided. You can send feedback directly to my manager at:
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Aug 7 '08 #10

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