alphabetizing array of objects by string (name)

Question

I am VERY new to programming, and am learning C#. Week 4!

Writing program asking for user input for:

Friends name
Phone
Month of Birth
Day
Year of birth.

Creating as an array of objects and using the IComparable to enable object comparison. Need to sort objects by string, alphabetically, and I think I have all the rest of the code except getting the string to compare. Here's what I have for the IComparable.CompareTo(Object o):

int IComparable.CompareTo(Object o)
{
    int returnVal;

    Friend temp = (Friend)o;
    if(this.Name > temp.Name)
        returnVal = 1;
    else
        if(this.Name < temp.Name)
            returnVal = -1;
        else returnVal = 0;
    return returnVal;
}

The error I receive when compiling is:

CS0019 Operator'>' cannot be applied to operands of type 'string' and 'string'.

Instructor is not much help, text doesn't synthesize this contingency.

Ry- · Accepted Answer · 2012-07-28 23:41:29Z

3

Just delegate to String.CompareTo:

int IComparable.CompareTo(Object o) {
    Friend temp = (Friend)o;

    return this.Name.CompareTo(temp.Name);
}

answered Jul 28, 2012 at 23:41

Ry-♦

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1 Comment

svick Over a year ago

You should be aware that this performs “case-sensitive and culture-sensitive comparison using the current culture”, which may or may not be what's required.

NPSF3000 · Accepted Answer · 2012-07-29 00:49:16Z

0

This uses a couple language features you are probably not used to, but does make like a little easier:

people = people.OrderBy(person => person.Name).ToList();

Used like:

var rnd = new Random();
var people = new List<Person>();
for (int i = 0; i < 10; i++)
    people.Add(new Person { Name = rnd.Next().ToString() });

//remember, this provides an alphabetical, not numerical ordering,
//because name is a string, not numerical in this example.
people = people.OrderBy(person => person.Name).ToList();

people.ForEach(person => Console.WriteLine(person.Name));
Console.ReadLine();

Google LINQ [and remember to add 'using System.Linq;'] and Lambda's.

answered Jul 29, 2012 at 0:49

NPSF3000

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