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Eval a string in C#

Posted on 2004-08-11
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20,707 Views
Last Modified: 2012-06-27
How do I evaluate a string in C#?  Example:

string myVarName = "sTest";
eval("string "+myVarName+" = \"<p>Value of string goes here</p>\"");
Response.Write(eval(myBarName));


Should output:
<p>Value of string goes here</p>
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Question by:hendridm
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10 Comments
 
LVL 5

Expert Comment

by:jjacksn
ID: 11774908
This is not really want you want, but might point you in the correct direction

using System;
using System.Reflection ;

namespace ConsoleApplication4
{
     /// <summary>
     /// Summary description for Class1.
     /// </summary>
     class Class1
     {

          private class foo {
               private int bar;
               public int Bar {
                    get { return bar; }
                    set { bar = value ; }
               }
               public foo() {}
          }


          static object GetProperty(string Name, object Obj) {
               PropertyInfo p = Obj.GetType().GetProperty(Name) ;
               if(p!=null) {
                    if(p.CanRead) {
                         return p.GetValue(Obj, null) ;
                    } else {
                         throw new System.Exception(Name + " is a WriteOnly property cannot read value") ;
                    }
               } else {
                    throw new System.ArgumentOutOfRangeException(Name) ;
               }
          }

          [STAThread]
          static void Main(string[] args)
          {
               foo f = new foo();
               f.Bar = 37;
               object o = GetProperty("Bar", f);
               Console.WriteLine("f.Bar = " + o.ToString() );
          }
     }
}
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LVL 5

Assisted Solution

by:jjacksn
jjacksn earned 50 total points
ID: 11774919
0
 
LVL 5

Assisted Solution

by:jjacksn
jjacksn earned 50 total points
ID: 11774954
After reading around, I don't think there is an equivelent to the JScript eval command.  

http://www.dotnet247.com/247reference/msgs/6/31515.aspx.  If you want to literally execute the strings, it looks like you will have to compile assemblies at run time.
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LVL 37

Expert Comment

by:gregoryyoung
ID: 11775000
theres a more recent thread (from yesterday in fact) http://www.experts-exchange.com/Programming/Programming_Languages/C_Sharp/Q_21088360.html

System.Web.UI.DataBinder.Eval() is what you want.
0
 
LVL 8

Author Comment

by:hendridm
ID: 11775017
Ok, thanks.  To be more specific, is there a way to do this?

string myVar = "Literal1";
Literal1.Text = "Lorem Ipsum";

Is there a way to programmatically specify 'Literal1', like so:

string myVar = "Literal1";
<name of variable in 'myVar'>.Text = "Lorem Ipsum";

If not, no problem.  You essentially answered my question anyway.
0
 
LVL 37

Assisted Solution

by:gregoryyoung
gregoryyoung earned 25 total points
ID: 11775043
for that you would be best off to use reflections ...
0
 
LVL 96

Expert Comment

by:Bob Learned
ID: 11783603
Are you talking about using Inline code with ASP.NET?

Bob
0
 
LVL 96

Expert Comment

by:Bob Learned
ID: 11783683
Something like this:

(1)  Define a page-level variable in public variable in the code-behind:

    Public var_value As Integer = 5

(2)  Use the HTML design to use the following inline code:

<p><%=var_value%></p>

The page will display 5 within the block.

Bob
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LVL 37

Expert Comment

by:gregoryyoung
ID: 11785062
for the above you could also use FindControl() ...
0
 
LVL 20

Accepted Solution

by:
ihenry earned 175 total points
ID: 11803153
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