How to evaluate in C# a string of expression

[Zeng]

Hello,
Please help!!! I've been stuck on this issue for months. I just wonder if
there is a way to programmaticall y evaluate expression
strings such as
( ( 3 + 5 ) / 2 ) > 4 --> this should return 0 or false( ( 3 + 6 ) / 3 ) >
( ( 5 + 3 ) / 4 ) --> this should return 1 or trueThanks for any comment or
advice.

There was an old post fro Scott Alen but I couldn't follow what he refered
to to make it happens. Currently I have to parse and evaluate the
expression myself and it's messy and very slow. Thanks for any comment and
advise.

Zeng

[Patrick]

Try this:

textBox1.Text = (3 + 5 / 2 > 4).ToString();
textBox2.Text = ((3 + 5) / 2 > 4).ToString();
"Zeng" <Ze******@hotma il.com> wrote in message
news:uG******** ******@TK2MSFTN GP09.phx.gbl...

Hello,
Please help!!! I've been stuck on this issue for months. I just wonder if there is a way to programmaticall y evaluate expression
strings such as
( ( 3 + 5 ) / 2 ) > 4 --> this should return 0 or false( ( 3 + 6 ) / 3 )

( ( 5 + 3 ) / 4 ) --> this should return 1 or trueThanks for any comment or advice.

There was an old post fro Scott Alen but I couldn't follow what he refered
to to make it happens. Currently I have to parse and evaluate the
expression myself and it's messy and very slow. Thanks for any comment and advise.

Zeng

[Peter Wone]

I can think of at least three ways to do this without rolling your own
interpreter.

(a) You can invoke the C# compiler on it and compile into memory. This
approach requires you to be extremely confortable with reflection in order
to instantiate and talk to the object you create.

(b) You can host the Windows Scripting Host engine and use javascript or
VBScript (or perl or whatever rings your bell) to parse and evaluate
expressions.

(c) You can pay me to write you a component that does (a) or (b).

[Cor Ligthert]

Zeng,

I still did not try this one.

\\\Eval by Nigel Amstrong
1. Create a file called: DynamicMath.js
2. Add this code to it:

class DynamicMath
{
static function Eval(MathExpres sion : String) : double
{
return eval(MathExpres sion);

};
}

3. Compile it with the command line jsc compiler: jsc /t:library
DynamicMath.js
4. Add a reference to DynamicMath.dll to your project (and to
Microsoft.JScri pt.dll as well)
5. Use from your favourite .NET language:
Dim d As Double = DynamicMath.Eva l("2 + 3 + 4")
MessageBox.Show (d)
6. That's it..
///

Maybe you can do

Cor
"Zeng" <Ze******@hotma il.com> schreef in bericht
news:uG******** ********@TK2MSF TNGP09.phx.gbl. ..

Hello,
Please help!!! I've been stuck on this issue for months. I just wonder
if
there is a way to programmaticall y evaluate expression
strings such as
( ( 3 + 5 ) / 2 ) > 4 --> this should return 0 or false( ( 3 + 6 ) / 3 )

>

( ( 5 + 3 ) / 4 ) --> this should return 1 or trueThanks for any comment
or
advice.

There was an old post fro Scott Alen but I couldn't follow what he refered
to to make it happens. Currently I have to parse and evaluate the
expression myself and it's messy and very slow. Thanks for any comment
and
advise.

Zeng

[Niki Estner]

"Zeng" <Ze******@hotma il.com> wrote in
news:uG******** ********@TK2MSF TNGP09.phx.gbl. ..

Hello,
Please help!!! I've been stuck on this issue for months. I just wonder
if
there is a way to programmaticall y evaluate expression
strings such as
( ( 3 + 5 ) / 2 ) > 4 --> this should return 0 or false( ( 3 + 6 ) / 3 )

>

( ( 5 + 3 ) / 4 ) --> this should return 1 or trueThanks for any comment
or
advice.

There was an old post fro Scott Alen but I couldn't follow what he refered
to to make it happens. Currently I have to parse and evaluate the
expression myself and it's messy and very slow. Thanks for any comment
and
advise.

If you're only trying to evaluate simple mathematical expressions, building
your own parser might be an option: Most parser generators (like ANTLR) come
with a "calc"-sample already, it's usually not much work to add one or two
operators.

Niki

[Alexei Cioina]

Hi Zeng,
try
1. info.lundin.Mat h from http://www.lundin.info/
2. Complex & DateTime Parser assembly for .NET from
http://www.geocities.com/alexei_cioina/cioinaeval.html

"Zeng" wrote:

Hello,
Please help!!! I've been stuck on this issue for months. I just wonder if
there is a way to programmaticall y evaluate expression
strings such as
( ( 3 + 5 ) / 2 ) > 4 --> this should return 0 or false( ( 3 + 6 ) / 3 ) >
( ( 5 + 3 ) / 4 ) --> this should return 1 or trueThanks for any comment or
advice.

There was an old post fro Scott Alen but I couldn't follow what he refered
to to make it happens. Currently I have to parse and evaluate the
expression myself and it's messy and very slow. Thanks for any comment and
advise.

Zeng

[info]

Zeng wrote:

Hello,
Please help!!! I've been stuck on this issue for months. I just wonder if there is a way to programmaticall y evaluate expression
strings such as
( ( 3 + 5 ) / 2 ) > 4 --> this should return 0 or false( ( 3 + 6 ) / 3 ) > ( ( 5 + 3 ) / 4 ) --> this should return 1 or trueThanks for any comment or advice.

There was an old post fro Scott Alen but I couldn't follow what he refered to to make it happens. Currently I have to parse and evaluate the
expression myself and it's messy and very slow. Thanks for any comment and advise.

Zeng

Hi Zeng,

You can do this with the DotBasic runtime, which is completely free.

In the download package there is a CSharp source file showing how to do
inline evaluation.

Here are the relevent lines:

....
using DotBasicRuntime ;
private Runtime runtime;
....
runtime = new Runtime();
object result = runtime.Eval(in putText.Text);
....

Testing the examples you posted:

runtime.Eval("( ( 3 + 5 ) / 2 ) > 4") returned False

runtime.Eval("( ( 3 + 6 ) / 3 ) > ( ( 5 + 3 ) / 4 )") returned True
The Eval statement can handle any legal DotBasic expression or program.
http://dotbasicscript.com

Regards,

-- Peter Fisk

[John Lee]

I think the easiest way to do is to create a jscript.net class with eval
function and use jsc.exe to compile it as library dll and then reference it
in your C# project.

John
"Zeng" <Ze******@hotma il.com> wrote in message
news:uG******** ********@TK2MSF TNGP09.phx.gbl. ..

Hello,
Please help!!! I've been stuck on this issue for months. I just wonder
if
there is a way to programmaticall y evaluate expression
strings such as
( ( 3 + 5 ) / 2 ) > 4 --> this should return 0 or false( ( 3 + 6 ) / 3 )

>

( ( 5 + 3 ) / 4 ) --> this should return 1 or trueThanks for any comment
or
advice.

There was an old post fro Scott Alen but I couldn't follow what he refered
to to make it happens. Currently I have to parse and evaluate the
expression myself and it's messy and very slow. Thanks for any comment
and
advise.

Zeng

[Nicole Schenk]

Zeng wrote:

Hello,
Please help!!! I've been stuck on this issue for months. I just wonder
if there is a way to programmaticall y evaluate expression
strings such as
( ( 3 + 5 ) / 2 ) > 4 --> this should return 0 or false( ( 3 + 6 ) / 3 )

( ( 5 + 3 ) / 4 ) --> this should return 1 or trueThanks for any comment
or advice.

There was an old post fro Scott Alen but I couldn't follow what he refered
to to make it happens. Currently I have to parse and evaluate the
expression myself and it's messy and very slow. Thanks for any comment
and advise.

Zeng

Look in the compiler access. It is possible to compile on the fly.

[Nicole Schenk]

Zeng wrote:

Hello,
Please help!!! I've been stuck on this issue for months. I just wonder
if there is a way to programmaticall y evaluate expression
strings such as
( ( 3 + 5 ) / 2 ) > 4 --> this should return 0 or false( ( 3 + 6 ) / 3 )

( ( 5 + 3 ) / 4 ) --> this should return 1 or trueThanks for any comment
or advice.

There was an old post fro Scott Alen but I couldn't follow what he refered
to to make it happens. Currently I have to parse and evaluate the
expression myself and it's messy and very slow. Thanks for any comment
and advise.

Zeng

Another easier solution:
1. make an ascx file with language="jscri pt"
2. make a function in this that says evaluate with one parameter sExpression
the expression as a string
3. in the function say
return eval(sExpressio n);

That should do it.
Thanks