5.10 Combine Strings into a Larger String

Problem

You want to combine several separate strings into a single string.

Solution

Use PowerShell’s unary -join operator to combine separate strings into a larger string using the default empty separator:

PS > -join ("A","B","C")
ABC

If you want to define the operator that PowerShell uses to combine the strings, use PowerShell’s binary -join operator:

PS > ("A","B","C") -join "`r`n"
A
B
C

To use a cmdlet for features not supported by the -join operator, use the Join-String cmdlet:

PS > 1..5 | Join-String -DoubleQuote -Separator ','
"1","2","3","4","5"

Discussion

The -join operator provides a natural way to combine strings. When used with no arguments (the unary join operator), it joins the list using the default empty separator. When used between a list and a separator (the binary join operator), it joins the strings using the provided separator.

Aside from its performance benefit, the -join operator solves an extremely common difficulty that arises from trying to combine strings by hand.

When first writing the code to join a list with a separator (for example, a comma and a space), you usually end up leaving a lonely separator at the beginning or end of the output:

PS > $list = "Hello","World"
PS > $output = ""
PS >
PS > foreach($item in $list)
{
    $output += $item + ", "
}

PS > $output
Hello, World,

You can resolve this by adding some extra logic to the foreach loop:

PS > $list = "Hello","World"
PS > $output = ""
PS >
PS > foreach($item in $list)
{
    if($output -ne "") { $output += ", " }
    $output += $item
}

PS > $output
Hello, World

Or, save yourself the trouble and use the -join operator directly:

PS > $list = "Hello","World"
PS > $list -join ", "
Hello, World

If you have advanced needs not covered by the -join operator, the .NET methods such as [String]::Join() are of course available in PowerShell.

For a more structured way to join strings into larger strings or reports, see Recipe 5.6.

5.10 Combine Strings into a Larger String

Problem

Solution

Discussion

See Also