what is a helper class?

[Mike P]

I have heard about helper classes, but can somebody please explain to me
what they are and what they are used?

 

[Jon Skeet [C# MVP]]

I have heard about helper classes, but can somebody please explain to me
what they are and what they are used?

They're usually classes just with static methods acting on another
class. Something like:

public static class StringHelper
{
public static string Reverse(string input)
{
(Code goes here)
}
}

 

[Guest]

"Helper class" is just a term to refer to a class that provides methods that
"help" do something. A well - know example is the Data Access Application
Blocks v2 "SqlHelper" class, which helps perform common data access functions.

-- Peter
Recursion: see Recursion
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[Guest]

Another example is : HttpUtility class.

 

[Mike P]

Jon,

What would be the reason for creating a class just with static methods
acting on another class?


Thanks,

Mike

 

[Jon Skeet [C# MVP]]

What would be the reason for creating a class just with static methods
acting on another class?

It collects them together. Often you can't add methods to a class
itself, because you don't have the code - I can't add the Reverse
method to string, for example.

If you're going to frequently do the same things with an instance of a
class, it's worth putting that somewhere rather than repeating the
code.

Another example is in my miscellaneous utility library
(http://pobox.com/~skeet/csharp/miscutil) - I've got a helper class for
working with streams. It has a set of methods to copy the contents of
one stream to another, and another set to read the complete contents of
a stream as a byte array.

 

[John Vottero]

It collects them together. Often you can't add methods to a class
itself, because you don't have the code - I can't add the Reverse
method to string, for example.

You can with C# V3.0 by adding "this" to the methods argument, ie:

public static class StringHelper
{
public static string Reverse(this string input)
{
(Code goes here)
}
}

....

using StringHelper;

string myString;
....

string reveresedString = myString.Reversed();