[ssis] How do I convert number to string and pass it as argument to Execute Process Task?

I am using Execute Process task in SSIS 2008 R2. I have a variable idVar which is of data type Int32. I need to pass this variable to property Arguments of the task so the process executable can take this variable as argument. I use expression to assign @idVar to Arguments.

Now the system says I need to convert Int to String so I used the following expression in the expression builder

(DT_STR, 10, 1252) @[User::IdVar] 

It gives the following error:

Expression cannot be evaluated.

Additional information:
The expression "(DT_STR, 10, 1252) @[User:IdVar]" has a result type of "DT_STR", 
which cannot be converted to a supported type.

(Microsoft.DataTransformationServices.Controls)

What is the correct way to type cast the number to string?

Error

This question is related to ssis

The answer is


Expression: "Total Count: " + (DT_WSTR, 11)@[User::int32Value]

for Int32 -- (-2,147,483,648 to 2,147,483,647)


Expression: "Total Count: " + (DT_WSTR, 5)@[User::Cnt]