Dowst.Dev

$string = "1. Computer name:DC-G11-FTW.contoso.com"
[regex]::Replace($string,"[^0-9a-zA-Z]","")

Uses a regex expression with replace to remove all characters that do not match the expression.

PS C:\> $string = "1. Computer name:DC-G11-FTW.contoso.com"
>> [regex]::Replace($string,"[^0-9a-zA-Z]","")

1ComputernameDCG11FTWcontosocom

$string = "1. Computer name:DC-G11-FTW.contoso.com"
[regex]::Replace($string,"[^0-9a-zA-Z ]","")

Uses a regex expression with replace to remove all characters that do not match the expression.

PS C:\> $string = "1. Computer name:DC-G11-FTW.contoso.com"
>> [regex]::Replace($string,"[^0-9a-zA-Z ]","")

1 Computer nameDCG11FTWcontosocom

$string = 'Thank you for calling 555-5757 your order total is $123.32'
$string -Replace "[0-9]","0"

Use the -Replace to Replace String using a regular expression

PS C:\> $string = 'Thank you for calling 555-5757 your order total is $123.32'
>> $string -Replace "[0-9]","0"

Thank you for calling 000-0000 your order total is $000.00

$string = 'The quick brown fox jumps over the lazy dog'
$string.Replace("brown","red")

Use the .Replace to Replace String using a plain text value

PS C:\> $string = 'The quick brown fox jumps over the lazy dog'
>> $string.Replace("brown","red")

The quick red fox jumps over the lazy dog