列表中的排序算法

Question

I'm trying to sort my list using an algorithm. The list contains string arrays which holds date, titel and entry.

So the error message I am getting is this:

Error CS0019 Operator '>' cannot be applied to operands of type 'string[]' and 'string[]'

I will not include all of my code, as it is not in English anyway.

List<string[]> loggBok = new List<string[]>();

        void nyttInlägg(string datum, string titel, string text) // När användaren anropar denna metoden från menyn, så kommer hans input
                                                                 // läggas in i vektorn. 
        {
            string[] anteckingar = new string[3] { "", "", "" };
            anteckingar[0] = datum;
            anteckingar[1] = titel;
            anteckingar[2] = text;
            loggBok.Add(anteckingar);

            
            
            bool isSorted = false;
            while (!isSorted)
            {
                isSorted = true;
                for (int i = 0; i < loggBok.Count - 1; i++)
                {
                    if ((loggBok[i]) > loggBok[i + 1])
                    {
                        string[] temp = loggBok[i + 1];
                        loggBok[i + 1] = loggBok[i];
                        loggBok[i] = temp;
                    }

                    i = i + 2;
                }
            }

So basically, every 3 element in the list will hold a stringarray with a date. This is the date that I want to organize. I believe I understand the logic behind the algorithm but I just cannot get the syntax right. I have checked other threads, some with similar problems but none that was 100%. As this is a school project it has to be an algorithm, thus I don't want to make it "easier" or more effective in anyway. Any ideas on how to overcome this horrible error message?

Answer 1

Some issues:

• if ((loggBok[i]) > loggBok[i + 1]) lacks a closing parenthesis

• The above attempts to compare arrays , while you just want to compare the dates. So you need to reference the date-entry in loggBok[i] :

   if ((loggBok[i][0]) > loggBok[i + 1][0]))

• The i index refers to arrays (triplets), so you should not increase it with three, but just with one, as it will go to the next triplet when you do i++ , which is what you want. So remove i = i + 2 , otherwise you skip some of these triplets.

Answer 2

The operator > greater than cannot be applied to type array or type string ( as mentioned in other answer comment) - have a look at the documentation here

Each element in the list is an array of strings - with structure:

1. Data
2. Title
3. Text

So the following command will fails if ((loggBok[i]) > loggBok[i + 1])) as you comparing two arrays with the operator > .

To retrieve the data you will have loggBok[i][0] which is a string. You need to convert them to the correct type(eg. int) in order to use the comparison operator > .

I assumed the data is a type int -

                if (int.TryParse(loggBok[i][0], out int currentElement) && 
                    int.TryParse(loggBok[i + 1][0], out int nextElement) && 
                    currentElement > nextElement)
                {
                    string[] temp = loggBok[i + 1];
                    loggBok[i + 1] = loggBok[i];
                    loggBok[i] = temp;
                }

You can read about the TryParse here