对象集合中的属性计数

Question

I'm struggling how to get my head round this issue.

I have a class which stores cell information for each cell in a spreadsheet.

public class Datacollection 
{
    public int rowNumber { get; set; }
    public string colName { get; set; }
    public string colValue { get; set; }
}

Elsewhere I then load an excel spreadsheet as a collection of these objects

private static List<Datacollection> _dataCol = new List<Datacollection>();

The spreadsheet I'm loading has 3 columns and 3000 rows, so the size of my collection is 9000. One Datacollection object for each cell in the spreadsheet.

How might I get a row number count from this collection? I guess I would need the highest value of 'rowNumber' but I'm not sure how to get this value back.

Many thanks,

Answer 1

If the row numbers are consecutive and start from 1, you can simply use LINQ's Max extension:

var rowCount = _dataCol.Max(cell => cell.rowNumber);

But if they do start at an arbitrary number instead of 1, or if there are gaps in the row numbers, you'd need to find the count of distinct row numbers:

var rowCount = _dataCol.Select(cell => cell.rowNumber).Distinct().Count();

---

If you are sure that every row has exactly three columns, a faster way would of course be var rowCount = _dataCol.Count / 3;

Answer 2

要获取rowNumber的最大值，可以使用LinQ：

var rowCount = _dataCol.Max(x => x.rowNumber);