Several methods of combining variables, numbers and strings together are demonstrated below.
In choosing the best method to use, consider the data types you will be working with carefully because PowerShell will treat string data and numbers very differently.
Concatenate strings:
PS C:\> $demo = 'abc' + 'def'
PS C:\> $demo
abcdef
Concatenate string variables:
PS C:\> $string1 = 'abc'
PS C:\> $string2 = 'def'
PS C:\> $string1 + ", " + $string2
abc, defPS C:\> $text = 'Hello'
PS C:\> $text += 'world'
PS C:\> $text
Helloworld
For longer expressions this can be spread over several lines with line breaks:
PS C:\> $string1 +
", " +
$string2
abc, def
Concatenate numbers with strings:
PS C:\> $int1 = 42
PS C:\> $string2 = 'def'
PS C:\> $int1 + ", " + $string2
Cannot convert value "," to type "System.Int32". Error: "Input string was not in a correct format."
The expression above is evaluated from left to right so converting the string to an integer fails, if we swap around the order they will both convert to a string without error:
PS C:\> $string2 + ", " + $int1
def, 42
String substitution - surround the whole expression in quotes, everything is evaluated as a string:
PS C:\> ”$int1, $string2”
42, defString Substitution has one important limitation: PowerShell will identify each variable in the expression by matching characters, that are legal for a $variable name, as soon as the first non-legal character is found (a space, comma or full stop) that matching stops.
This means that a subexpression like $object.property will be read as just $object
Explicit sub-expression expansion:
PS C:\> "$($int1), $($string2)"
42, def
Single or Double quoted strings can both be expanded:
$sq = 'a single quoted string'
$dq = "a double quoted string"
PS C:\> "$sq--$dq"
a single quoted string--a double quoted string
Within a single quoted expression no variables are expanded:
PS C:\> '$sq--$dq'
$sq--$dq
Substitution with the -f operator
PS C:\> "{0}--{1}" -f $sq,$dq
a single quoted string--a double quoted string
Join with the -join operator:
PS C:\> $sq,$dq -join ", "
a single quoted string, a double quoted string
A further nuance that often catches people out is that Write-host by default adds a single space separator between items, to remove that you must specify an empty string '' as the separator:
PS C:\> $one = 'one'
PS C:\> $two = 'two'
PS C:\> Write-Host $one $two
one twoPS C:\> Write-Host $one $two -separator ''
onetwo
Using the .Net concat() method:
PS C:\batch> [System.String]::Concat("abc","def", "ghi")
abcdefghi
An alternative concatenation method is to use a StringBuilder .Net object, this has the advantage of being much faster which may be important when working with long strings or repeatedly in a loop.
$stringbuilder = New-Object -TypeName System.Text.StringBuilder
$null = $stringbuilder.Append("Hello")
$null = $stringbuilder.Append("World")
$stringbuilder.ToString()
“I hope someday you’ll join us, and the world will be as one” ~ John Lennon
Methods - ToUpper(), PadRight(), Split(), Substring(), Replace() etc.
The -f operator