Append a Lists Contents to another List C#

Question

I have the following:

A main List called GlobalStrings
Another List called localStrings

In a loop for example:

List<string> GlobalStrings = new List<string>(); 
List<string> localStrings = new List<string>();
for(x=1;x<10;x++)
{
    localStrings.Add("some value"); 
    localStrings.Add("some value");
}
// Want to append localStrings to GlobalStrings as easily as possible

You are doing it wrong, `localStrings = new List;` should be placed before the `for` loop — Wassim AZIRAR, Dec 07 '14 at 19:59
Wassim, I think that's why he differentiates between local and global; localStrings is local to the for-loop scope, GlobalStrings is in the global scope. — Dagrooms, Jun 12 '15 at 16:15
This is a poor example (that invites totally wrongheaded comments like Wassim's), since obviously you could just `Add` to `GlobalStrings` instead of to `localStrings`. And FWIW you loop only runs 9 times. Better would be `for (int x = 0; x < 10; ++x) {var localStrings = GetAListOfStrings(); /* append those to GlobalStrings */}` — Jim Balter, Nov 10 '18 at 20:06

score 330 · Accepted Answer · edited Oct 12 '19 at 06:01

330

GlobalStrings.AddRange(localStrings);

Note: You cannot declare the list object using the interface (IList).
Documentation: List<T>.AddRange(IEnumerable<T>).

edited Oct 12 '19 at 06:01

Cœur

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answered Dec 01 '09 at 11:29

Lee

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score 60 · Answer 2 · edited Oct 12 '19 at 06:01

60

GlobalStrings.AddRange(localStrings);

That works.

Documentation: List<T>.AddRange(IEnumerable<T>).

edited Oct 12 '19 at 06:01

Cœur

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answered Dec 01 '09 at 11:29

Jimmeh

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While correct, this answer now stands as a duplicate of Lee's answer. – Cœur Oct 12 '19 at 05:58

score 22 · Answer 3 · answered Dec 01 '09 at 11:31

22

Try AddRange-method:

GlobalStrings.AddRange(localStrings);

answered Dec 01 '09 at 11:31

martin

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While correct, this answer now stands as a duplicate of Lee's answer. – Cœur Oct 12 '19 at 06:03

score 8 · Answer 4 · answered Dec 01 '09 at 11:28

8

With Linq

var newList = GlobalStrings.Append(localStrings)

answered Dec 01 '09 at 11:28

Blake Pettersson

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3

Append doesn't seem to exist? Do you have a link to MSDN doc for it? – Pod May 31 '16 at 21:41
5

Perhaps you meant Concat ... though that would mean a lot of copying, and is a good illustration of how *not* to use LINQ. – Jim Balter Nov 10 '18 at 20:07

score 6 · Answer 5 · answered Aug 13 '12 at 20:43

Here is my example:

    private List<int> m_machinePorts = new List<int>();

    public List<int> machinePorts
    {
        get { return m_machinePorts; }
    }

    Init()
    {
        // Custom function to get available ethernet ports
        List<int> localEnetPorts = _Globals.GetAvailableEthernetPorts();

        // Custome function to get available serial ports
        List<int> localPorts = _Globals.GetAvailableSerialPorts();

        // Build Available port list 
        m_machinePorts.AddRange(localEnetPorts);
        m_machinePorts.AddRange(localPorts);
     }

score 2 · Answer 6 · answered Dec 01 '09 at 12:14

2

if you want to get "terse" :)

List<string>GlobalStrings = new List<string>(); 

for(int x=1; x<10; x++) GlobalStrings.AddRange(new List<string> { "some value", "another value"});

answered Dec 01 '09 at 12:14

BillW

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Append a Lists Contents to another List C#

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