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Var vs. Object data type in C#
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| Knowing which data type to use in different situations is generally a
basic level decision. I mean you do not need to think very hard about storing regular
numbers or storing words. I hope you don't believe that. Actually, choosing the correct
data type to store your data can have serious implication on memory, storage, percision
and access. So spend some time learning and studying the different data types and try
to imagine which situations you would use a string for or perhaps a float. |
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| This article will cover 2 data types. First we will discuss the var
data type. The var is a nice one because you do not need to decide whether to use
a System.String or System.Int32 becuase when you associate a value to the var, the
compiler will determine the type for you. NOTE: using var does not remove the
responsibility from understanding the memory usage, storage usage, percision,
etc..of the data type. It's just makes things a bit eaiser and faster, but use
it with caution. |
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| You see above that I set str to a string, intg to an integer and
dec to a decimal value and the compiler determined which data type to convert
var to. With var you will get access to the the data type class properties and
members as you see from the drop downs. The same is not true for an object.
It is not known at compile time what data type the value stored within the
object is. You can store classes or generic lists in an object. I.e. both
reference and value types can be stored in an object. |
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| Similar situation if you have a simple class named Person: |
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public class Person
{
public string Name { get; set; }
public string Age { get; set; }
}
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| If I use var to contain the class, then the properties within the
class are available, however if I use object they are not. |
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| When to use an object in C#? I use object variables in situations
when I will receive a list of data but a m not certain of the data types within
them. For example: |
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List<object> fields = new List<object>(BuildFieldList(Query));
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| The Query identified above is a string of columns a user has
selected from a reporting tool. I am not certain which column or how many the
user has selected. Therefore I decided to use an object variable. |
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| When to use a var in C#? Following along the same line as the above
example, I would use a var to contain the result set from the Query that was
executed. |
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| Posts: 113 |
| Comments:
86 |
| Fundamentals:
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The sample code on this website is provided to illustrate a concept and should not be used in
applications or Web sites without proper professional consultation, as it may not illustrate
the safest coding practices. I assume no liability for incidental or consequential damages
should the sample code be used for purposes other than as intended.
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