Method returning string but is assigned as string[] - powershell

Question

I have this code:
[string]$emailBody = getEmailBody $firstName $emailTemplateFileContent
function getEmailBody($firstName, $emailTemplateFileContent)
{
$sb = New-Object Text.StringBuilder
for ($i = 1; $i -lt $emailTemplateFileContent.Length; $i++)
{
$sb.AppendLine($emailTemplateFileContent[$i])
}
$emailTemplateText = $sb.ToString()
$emailTemplateTextCustomised = $emailTemplateText.Replace("#name", $firstName)
return $emailTemplateTextCustomised
}
When I type $emailTemplateTextCustomised.getType() I can see that it is a string.
However when I type $emailBody.getType() I can see that it is an Array.
I can also see that the array has 8 strings, each string containing the output from getEmailBody().
UPDATE:
Powershell seems really buggy, it is no longer a String[] but just a String with 8 repetitions of the output from getEmailBody().
Why is it doing this?
Thanks in advance.

Answer 1

PowerShell isn't buggy, well at least not in this case. :-) You have to understand that in PowerShell the "output" of a function is anything that is not captured to a variable. The line that does the StringBuilder.AppendLine() returns the StringBuilder and that is added to the output of your function. Try this:
function getEmailBody($firstName, $emailTemplateFileContent)
{
$sb = New-Object Text.StringBuilder
for ($i = 1; $i -lt $emailTemplateFileContent.Length; $i++)
{
$sb.AppendLine($emailTemplateFileContent[$i]) > $null
}
$emailTemplateText = $sb.ToString()
$emailTemplateText.Replace("#name", $firstName)
}
If you are on V3 (maybe V2) you can use the -replace operator as well:
function getEmailBody($firstName, $emailTemplateFileContent)
{
$sb = New-Object Text.StringBuilder
for ($i = 1; $i -lt $emailTemplateFileContent.Length; $i++)
{
$sb.AppendLine($emailTemplateFileContent[$i]) > $null
}
$emailTemplateText = $sb.ToString() -replace '#name',$firstName
$emailTemplateText
}