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Merging two arrays in .NET

Tags:

arrays

c#

.net

People also ask

How do I combine two arrays?

To merge elements from one array to another, we must first iterate(loop) through all the array elements. In the loop, we will retrieve each element from an array and insert(using the array push() method) to another array. Now, we can call the merge() function and pass two arrays as the arguments for merging.

Can you add arrays in C#?

In C#, you cannot change the array size once is created. If you want something like arrays but be able to add/remove elements, use List<int>().

What is array initialization in C#?

Array InitializationYou can initialize the elements of an array when you declare the array. The length specifier isn't needed because it's inferred by the number of elements in the initialization list. For example: C# Copy. int[] array1 = new int[] { 1, 3, 5, 7, 9 };


In C# 3.0 you can use LINQ's Concat method to accomplish this easily:

int[] front = { 1, 2, 3, 4 };
int[] back = { 5, 6, 7, 8 };
int[] combined = front.Concat(back).ToArray();

In C# 2.0 you don't have such a direct way, but Array.Copy is probably the best solution:

int[] front = { 1, 2, 3, 4 };
int[] back = { 5, 6, 7, 8 };

int[] combined = new int[front.Length + back.Length];
Array.Copy(front, combined, front.Length);
Array.Copy(back, 0, combined, front.Length, back.Length);

This could easily be used to implement your own version of Concat.


If you can manipulate one of the arrays, you can resize it before performing the copy:

T[] array1 = getOneArray();
T[] array2 = getAnotherArray();
int array1OriginalLength = array1.Length;
Array.Resize<T>(ref array1, array1OriginalLength + array2.Length);
Array.Copy(array2, 0, array1, array1OriginalLength, array2.Length);

Otherwise, you can make a new array

T[] array1 = getOneArray();
T[] array2 = getAnotherArray();
T[] newArray = new T[array1.Length + array2.Length];
Array.Copy(array1, newArray, array1.Length);
Array.Copy(array2, 0, newArray, array1.Length, array2.Length);

More on available Array methods on MSDN.


Use LINQ:

var arr1 = new[] { 1, 2, 3, 4, 5 };
var arr2 = new[] { 6, 7, 8, 9, 0 };
var arr = arr1.Union(arr2).ToArray();

Keep in mind, this will remove duplicates. If you want to keep duplicates, use Concat.


If you don't want to remove duplicates, then try this

Use LINQ:

var arr1 = new[] { 1, 2, 3, 4, 5 };
var arr2 = new[] { 6, 7, 8, 9, 0 };
var arr = arr1.Concat(arr2).ToArray();