c# list how to insert a new value in between two values

so i have a list where i need to add new values constantly but when i do i need to increment it and insert it in between two values.

List<int> initializers = new List <int>();

initializers.Add(1);
initializers.Add(3);

so initializers would have 1, 3 values.

i would then process a new set of numbers. the initializers will need to have the values.

1, 5, 3, 7

and if i process another set of numbers it should become

1, 9, 5, 13, 3, 11, 7, 15

i know how to properly generate the new values inserted, i just need some help on inserting it in between the existing values of the initializers without having to add 2 or 3 more loops to move the values’ positions.

Answers:

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Method 1

List<int> initializers = new List <int>();

initializers.Add(1);
initializers.Add(3);

int index = initializers.IndexOf(3);
initializers.Insert(index, 2);

Gives you 1,2,3.

Method 2

Use List<T>.Insert:

initializers.Insert(index, value);

Method 3

You can just use List.Insert() instead of List.Add() to insert items at a specific position.

Method 4

For those who are looking for something more complex (inserting more than one item between 2 values, or don’t know how to find the index of an item in a list), here is the answer:

Insert one item between 2 values is dead easy, as already mentioned by others:

myList.Insert(index, newItem);

Insert more than one item also is easy, thanks to InsertRange method:

myList.InsertRange(index, newItems);

And finally using following code you can find the index of an item in list:

var index = myList.FindIndex(x => x.Whatever == whatever); // e.g x.Id == id

Method 5

Another approach, if there is a computationally viable way of sorting the elements, is:

list.Insert(num);
// ...
list.Insert(otherNum);

// Sorting function. Let's sort by absolute value
list.Sort((x, y) => return Math.Abs(x) - Math.Abs(y));

All methods was sourced from stackoverflow.com or stackexchange.com, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0