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7.7 Combine Two Arrays

Problem

You have two arrays and want to combine them into one.

Solution

To combine PowerShell arrays, use the addition operator (+):

PS > $firstArray = "Element 1","Element 2","Element 3","Element 4"
PS > $secondArray = 1,2,3,4
PS >
PS > $result = $firstArray + $secondArray
PS > $result
Element 1
Element 2
Element 3
Element 4
1
2
3
4

Discussion

One common reason to combine two arrays is when you want to add data to the end of one of the arrays. For example:

PS > $array = 1,2
PS > $array = $array + 3,4
PS > $array
1
2
3
4

You can write this more clearly as:

PS > $array = 1,2
PS > $array += 3,4
PS > $array
1
2
3
4

When this is written in the second form, however, you might think that PowerShell simply adds the items to the end of the array while keeping the array itself intact. This is not true, since arrays in PowerShell (like most other languages) stay the same length once you create them. To combine two arrays, PowerShell creates a new array large enough to hold the contents of both arrays and then copies both arrays into the destination array.

If your plan is to add and remove data from an array frequently, the System.Collections.ArrayList class provides a more dynamic alternative. For more information about using the ArrayList class, see Recipe 7.12.

7.7 Combine Two Arrays

Problem

Solution

Discussion

See Also