Return object from list of objects based on variable in C#

Question

I have a list of objects, of class Author, and I want to search this list of authors, based on one of the Author's properties, name, and when I receive a match I would like to return the instance of Author to be used to create an instance of another class, that requires Author as part of its constructor.

A better way to explain it would be:

author getAuthor(String arg_name)
{
  foreach (author auth in authorList)
  {
    if (auth.name == arg_name)
    {
      return auth;
    }
  }
}

Although I realize this specific code does work, is there a better way to perform this action?

Habib · Accepted Answer · 2014-03-03 20:33:39Z

8

You can use Enumerable.FirstOrDefault like:

return authorList.FirstOrDefault(a=> a.name == arg_name);

This would return null if any author with name doesn't matches with the parameter passed.

For your particular code, your check if (auth == arg_name) should give you compile time error. Your check should be if (auth.name == arg_name)

edited Mar 3, 2014 at 20:33

answered Mar 3, 2014 at 20:31

Habib

224k30 gold badges420 silver badges446 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

sh3rifme Over a year ago

Works great! Much more compact than a foreach, thanks! Now to wait the 9 minutes to accept your answer :|

Habib Over a year ago

@sh3rifme, start using LINQ this would make your code compact and it is fun to work with :)

sh3rifme Over a year ago

thanks for pointing that out! I keep meaning to use more LINQ but i'm only just getting started with C# and have needed a good resource to guide my newb self, i'll check that link (pun intended) out!

Matan Shahar · Accepted Answer · 2014-03-03 20:34:52Z

0

Assuming you have a public property of Name in the Author you should be able to to get its value and compare it to the requested value (in your case arg_name). One way is to use foreach:

foreach (author auth as authorList)
  {
    if (auth.name == arg_name)
    {
      return auth;
    }
  }

Another way is to use Linq:

return authorList.FirstOrDefault(r=> r.name == arg_name);

answered Mar 3, 2014 at 20:34

Matan Shahar

3,2402 gold badges22 silver badges45 bronze badges

Comments

Shlomi Borovitz · Accepted Answer · 2014-03-03 20:57:56Z

0

The LINQ solution, although compact and elegant, is inefficient. You could use a dictionary, mapping from name, to index inside the list. Take into account that this solution is inefficient in adding/removing items, especially if they're added/removed from the middle of that list.... Think about which solution is more appropriate for you

answered Mar 3, 2014 at 20:57

Shlomi Borovitz

1,7009 silver badges9 bronze badges

Collectives™ on Stack Overflow

Return object from list of objects based on variable in C#

3 Answers 3

3 Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

3 Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related