从对象列表中获取值列表

Question

I have a simple class:

 private class Category
    {
        public int Id { get; set; }
        public string Value { get; set; }
    }  

an also a list of objects of this type:

 List<Category> Categories;

I need to get a list of Ids that are in Categories list. Is there a simpler way to do this than using for loop like this:

 List<int> list = new List<int>();
    for (int i = 0; i < Categories.Count; i++)
    {
        list.Add(Categories[i].Id);
    }

Thanks in advance.

Answer 1

This expression gives you the list you want:

    Categories.Select(c => c.Id).ToList();

Also, don't forget

    using System.Linq;

Answer 2

Use as follows.

Categories.Select(c => c.Id).ToList();

||

List<int> list = new List<int>();
foreach (Category item in Categories)
{
    list.Add(item.Id);
}