C# for or foreach to create array from List

Question

What is the most elegant way to loop through a List, do something on each element and create an array from those items?

These two solutions both serve the purpose, but are there pros/cons to using one over the other or is there a more elegant way to achieve this in C#?

Example 1:

public void SomeFunc(List<Person> lst)
{
    PersonPrivate[] arr = new PersonPrivate[lst.Count];
    int idx = 0;
    lst.ForEach(x =>
    {
        PersonPrivate p = new PersonPrivate(convert(p.name), convert(p.lastname));
        arr[idx] = p;
        idx++;
    }

    SavePerson(arr);
}

Example 2:

public void SomeFunc(List<Person> lst)
{
     PersonPrivate[] arr = new PersonPrivate[lst.Count];
     for (int i = 0; i < lst.Count; i++)
     {
         PersonPrivate p = new PersonPrivate(convert(p.name), convert(p.lastname));
         arr[i] = p;
     }

     SavePerson(arr);
}

EDIT: I don't believe this question is precisely the same as the one marked as duplicate. Although that one provides useful info too the comparison is not between for and foreach and not specific to creating an array from list.

Typically this would be done with LINQ's .Select - is that a viable solution? — Scott
– Scott, Commented Aug 21, 2017 at 14:26
lst.Select(p => new PersonPrivate(convert(p.name), convert(p.lastname))).ToArray(); — Alexander Derck
– Alexander Derck, Commented Aug 21, 2017 at 14:26
Linq might make this easier: var privp = lst.Select(x => new(PersonPrivate(convert(x.name), convert(x.lastname))).ToArray(); — Kevin Cook
– Kevin Cook, Commented Aug 21, 2017 at 14:27
ForEach is almost always the wrong choice in my opinion (use foreach or Select depending on what you are trying to do). — crashmstr
– crashmstr, Commented Aug 21, 2017 at 14:27

Cory Nelson · Accepted Answer · 2017-08-21 14:59:23Z

5

Just use Select.

var arr = list
    .Select(p => new PersonPrivate(convert(p.name), convert(p.lastname)))
    .ToArray();
SavePerson(arr);

edited Aug 21, 2017 at 14:59

Cory Nelson

30.3k5 gold badges77 silver badges114 bronze badges

answered Aug 21, 2017 at 14:51

Márton Balassa

9578 silver badges11 bronze badges

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