Question: How do I convert function input parameters to the right type?

I want to return a string that has part of the URL passed into it removed.

**This works, but it uses a hard-coded string:**

```
function CleanUrl($input)
{
    $x = "http://google.com".Replace("http://", "")
    return $x
}

$SiteName = CleanUrl($HostHeader)
echo $SiteName

```

**This fails:**

```
function CleanUrl($input)
{
    $x = $input.Replace("http://", "")
    return $x
}

Method invocation failed because [System.Array+SZArrayEnumerator] doesn't contain a method named 'Replace'.
At M:\PowerShell\test.ps1:13 char:21
+     $x = $input.Replace( <<<< "http://", "")

```

Answer: 
```
function CleanUrl([string] $url)
{
    return $url.Replace("http://", "")
}

```
This worked for me:

```
function CleanUrl($input)
{
    return $input.Replace("http://", "")
}

```