如何计算 class 中每个科目学生的 position？

Question

ok to be more lucid. what i actually mean is this i have a datagrid with defferent columns such as Id column, firstname, and columns of deferent subjects below is the sample:

when each row from the sample datagrid is selected the all the scores for each subject column is shown in the textbox1. like this: sample before click event

and when the button1 event is clicked with code below:

 foreach(int mark in txtresult.ToString())
        {
            if (mark < 40)
            {
                string[] parts = txtresults.Text.Split(new char[] { ' ' }, StringSplitOptions.RemoveEmptyEntries);
                int[] numbers = parts.Select(p => int.Parse(p)).ToArray();
                **int maximum = numbers.Max();**
                int position = Array.IndexOf(numbers, maximum);
                parts[position] = "1".ToString();
                txtresults.Text = string.Join(" ", parts);
            }
            else if(mark >=40 && <50)
            {
                m="2th" position etc... within the above block of code
            }

sample after button click event

the score for each subject should be ranked according to specified range "if(mark <40)" but it is rather ranking only the Max(); values in the textbox and not the small values within the textbox also.

so my question is: how can i grade each student within the datagrid Like in: column English i want to be able to rank the highest student with 1st, and next highest with 2nd... etc. and wherever the loop meets similar score in the text box will have similar position and continue ranking. until all scores of each student are ranked; (eg. Eng =56, 78, 89, 76, 89.. from this 89 => 1st; 89 =>1st; 78 => 3rd; 76 =>4th position; & 56=>5th position;)

Answer 1

You can use LINQ to group items of a collection.

The following example creates three groups:
"Low", "Mid", "High" using a rule for values
n < 10 , n >= 10 && n < 100 , n >= 100 :

var numericString = "1 2 12 15 123 757";
var numberGroups = numericString
  .Split(' ', StringSplitOptions.TrimEntries | StringSplitOptions.RemoveEmptyEntries)
  .Select(numericString => int.Parse(numericString))
  .GroupBy(number => number < 10
    ? "Low" 
    : number < 100 
      ? "Mid" 
      : "High");

// Access the groups
foreach (IGrouping<string, int> numberGroup in numberGroups)
{
  string groupName = numberGroup.Key; // E.g. "High"
  IEnumerable<int> groupValues = numberGroup; // 123, 757
}

And to group equal values:

var numericString = "100 20 12 100 20 20 48 100";
var numberGroups = numericString
  .Split(' ', StringSplitOptions.TrimEntries | StringSplitOptions.RemoveEmptyEntries)
  .Select(numericString => int.Parse(numericString))
  .GroupBy(number => number);

// Access the groups
foreach (IGrouping<int, int> numberGroup in numberGroups)
{
  int groupName = numberGroup.Key; // E.g. 100
  List<int> groupValues = numberGroup.ToList(); // 100, 100, 100
}