why this code doesn't compile?

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Hi Everyone,

Can any one explain why the following code doesn't compile?

C#

int a = 7;
int b = 5;

dynamic oa = a;
dynamic ob = b;

int c = oa - ob;

Thanks in advance.

Posted 25-Feb-11 23:06pm

satyagrahi_2010

Updated 26-Feb-11 2:31am

Toli Cuturicu

v3

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OriginalGriff · Answer 1 · 2011-02-25T23:28:00

Solution 2

Are you using VS2010? If not, then dynamic is not available (it was added at V4.0)

Otherwise, what error do you get - it compiles clean and works for me...
"am using VS2010.
Getting same compilation Errors: Unexpected character'-'
Invalid expression term "
; expected
; expected"

Have you included your code inside a method?

C#

using System;

namespace ConsoleTester
    {
    class Program
        {
        static void Main(string[] args)
            {
            int a = 7;
            int b = 5;

            dynamic oa = a;
            dynamic ob = b;

            int c = oa - ob;
            Console.WriteLine(c);
            }
        }
    }

Posted 25-Feb-11 23:28pm

OriginalGriff

Updated 25-Feb-11 23:54pm

v2

Comments

satyagrahi_2010 26-Feb-11 5:49am

am using VS2010.
Getting same compilation Errors: Unexpected character'-'
Invalid expression term "
; expected
; expected

OriginalGriff 26-Feb-11 5:54am

Answer updated

Espen Harlinn 26-Feb-11 5:58am

Right :)

satyagrahi_2010 26-Feb-11 6:04am

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace MyPractice
{
class Program
{
static void Main(string[] args)
{

int a = 7;
int b = 5;
dynamic oa = (dynamic)a;
dynamic ob = (dynamic)b;
int c = oa – ob;

Console.WriteLine(" C Value is : "+c);

Console.ReadKey();
}
}

}
The above code is in my class file. i saw that project properties Target Framework is .NET Framework 4

satyagrahi_2010 26-Feb-11 6:18am

It's working fine in another system. thanks for helping me.

Espen Harlinn · Answer 2 · 2011-02-25T23:57:00

OriginalGriff is right, this compiles and runs nicely:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace SimpleTestCS
{
    class Program
    {
        static void Main(string[] args)
        {
            int a = 7; 
            int b = 5; 
            dynamic oa = a; 
            dynamic ob = b; 
            int c = oa - ob;
            Console.WriteLine(c);
        }
    }
}

So open your project properties and check that you are building for the .Net 4 runtime

Regards
Espen Harlinn

Sandeep Mewara · Answer 3 · 2011-02-25T23:23:00

Solution 1

You need explicit type conversion here.

Try:

C#

int a = 7;    
int b = 5;        
dynamic oa = (dynamic)a;    
dynamic ob = (dynamic)b;       
int c = oa - ob;

If needed, look here[^] for more clarity.

UPDATE:
1. As already said by OriginalGriff, your code would work fine if you have .NET framework 4.0
2. Based on the error, it's clear dynamic is not being considered as a keyword and hence an error
3. Look for the missing reference. Probably you are not using .NET framework 4.0, which would be needed here for dynamic keyword.

Posted 25-Feb-11 23:23pm

Sandeep Mewara

Updated 25-Feb-11 23:51pm

v2

Comments

OriginalGriff 26-Feb-11 5:30am

Actually, you don't: a default console project with his original lines of code compiles cleanly and runs ok in VS2010, I checked. Nasty thing to do, though - reminds me too much of VB var...

Sandeep Mewara 26-Feb-11 5:32am

Oh Ok. Thanks for telling me that. Good to know. :thumbs up:

Surely it is a bad idea to use something which will pass compile time and be checked only at runtime. Dangerous to use dynamic until unless really needed.

OriginalGriff 26-Feb-11 5:33am

Totally agree! It's a good way to hide errors: I can understand why MS included it, but I do wish they hadn't...

Sandeep Mewara 26-Feb-11 5:37am

It just gives few notorious coders to play around with if they like to. :P :)

satyagrahi_2010 26-Feb-11 5:48am

Sorry to say, explicit type conversion is not working.

Getting same compilation Errors: Unexpected character'-'
Invalid expression term "
; expected
; expected

Sandeep Mewara 26-Feb-11 5:50am

1. As already said by OriginalGriff, your code would work fine if you have .NET framework 4.0
2. Based on the error, it's clear dynamic is not being considered as a keyword and hence an error
3. Look for the missing reference. Probably you are not using .NET framework 4.0, which would be needed here for dynamic keyword.

satyagrahi_2010 26-Feb-11 5:57am

sorry to say: am sure am using VS2010 (.NET4.0)
i wrote that code in Console Application

Sandeep Mewara 26-Feb-11 6:00am

Using VS 2010 would not ensure you are using .NET 4.0.

Do right click on project and select properties. Look at the .NET Framework in application tab. You need to have it as 4.0

satyagrahi_2010 26-Feb-11 6:20am

Its working fine thanks for helping me.

Sandeep Mewara 26-Feb-11 6:21am

Good to know. :)