Arguments of constructor

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1.80/5 (2 votes)

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Hi,

I am using following code for calling single arguments of constructor

C#

List<MsgIdTimeStampMap> CANMsgIdList = new List<MsgIdTimeStampMap>();
          
           CANMsgIdList=  ReadLogFile(@"\\global.scd.scania.com\home\se\121\valhbc\Desktop\log files\log file with orange\logfile.asc");


           var ctors = typeof(MsgIdTimeStampMap).GetConstructors();

           var ctor = ctors[0];

           ParameterInfo[] pars = ctor.GetParameters();
           Console.WriteLine(pars[2]);
           Console.ReadKey();

Result on console:

System.String timestamp

This is working fine. But when I am trying to do something like this

C#

var ctors = typeof(CANMsgIdList[0]).GetConstructors();

It is giving some error like this

The type or namespace name 'CANMsgIdList' could not be found (are you missing a using directive or an assembly reference?

Array size cannot be specified in a variable declaration (try initializing with a 'new' expression)

Can anyone help me in solving this???

Thanks
John

Posted 20-Dec-13 3:04am

Member 10408451

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Comments

BillWoodruff 20-Dec-13 10:24am

This, and your previous question along the same lines, suggest to me you are having some difficult with examining Types at run-time, with inspecting constructor parameters, etc.

It might be helpful if you describe what your "big-picture" goal is here: why do you need to examine Types, or ctor parameters at run-time ? What type of data are you dealing with that this becomes necessary ? Is this a late-binding scenario where Types are unknown because code is being built on-the-fly ?

Sergey Alexandrovich Kryukov 20-Dec-13 11:30am

Exactly. So far, this is the best response. I doubt OP understands the bigger picture at all. (See also my comment below :-)
It's wonderful how many totally pointless "answers" was posted, only Ron found that a bug happens well before using reflection...
—SA

Sergey Alexandrovich Kryukov 20-Dec-13 11:23am

What does it mean, "single arguments"?
What does it mean, "calling argument" or "calling arguments"?
Why using reflection here at all? What's the purpose?
And so on...
—SA

3 solutions

Solution 4

typeof is an operator where GetType is a method. typeof take integral type as an argument where GetType provide type from object at runtime. 2 are different things and usage also different.

for details:
http://stackoverflow.com/questions/983030/type-checking-typeof-gettype-or-is[^]

In your case GetType() method is appropiate for retrive constructors.
Example:

C#

class Program
    {
        static void Main(string[] args)
        {
            var emp = new Employee(1, "A");
            var list = new List<employee>();
            list.Add(emp);
            var result = list[0].GetType().GetConstructors();
            
        }
    }

    public class  Employee
    {
        public int Id { get; set; }
        public string Name { get; set; }

        public  Employee(int id, string name)
        {
            Id = id;
            Name = name;
        }
    }

Posted 20-Dec-13 5:08am

S. M. Ahasan Habib

Updated 20-Dec-13 5:09am

v2

Solution 3

Try this..

C#

var ctors = CANMsgIdList[0].GetType().GetConstructors();

It is a compile error, u should use .GetType() instead of typeof(T) for this kind of situations.

read this excellent answer:
difference-of-getting-type-by-using-gettype-and-typeof[^]

Posted 20-Dec-13 3:50am

Karthik_Mahalingam

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Ron Beyer · Accepted Answer · 2013-12-20T03:22:00

Solution 2

Try:

C#

var ctors = CANMsgIdList[0].GetType().GetConstructors();

But you haven't posted all your code, because the error you are getting says that the variable CANMsgIdList can't be found in the current namespace. So you are trying to do that somewhere else that CANMsgIdList isn't defined. Please post the code you are using that doesn't work and I can better help you.

Posted 20-Dec-13 3:22am

Ron Beyer

Comments

Karthik_Mahalingam 20-Dec-13 9:55am

Ron, your answer is right.
its a compile error.. john should use GetType() instead of typeof()...

BillWoodruff 20-Dec-13 10:20am

+5 Bullseye.

Sergey Alexandrovich Kryukov 20-Dec-13 11:28am

I 5ed, too, but your comment to the question is better. :-)
The bigger problem is the purpose of using reflection here, very likely, by lack of understanding of the bigger picture by OP...
—SA