Converting Letters to Numbers and Bit Masks

Sometimes, you may need to turn characters such as drive letters into numbers or even bit masks. With a little bit of math, this is easily doable. Here is a sample:

Let's start with a dirty and unsorted list of drive letters. This is how PowerShell can sort and normalize them:

$DriveList = 'a', 'b:', 'd', 'Z', 'x:'

$DriveList |
    ForEach-Object { $_.toUpper()[0] } |

     Sort-Object

With a little more code, you get back drive indices, taking advantage of the ASCII code of characters:

$driveList = 'a', 'b:', 'd', 'Z', 'x:'
$DriveList |
    ForEach-Object { $_.toUpper()[0] } |
    Sort-Object |

    ForEach-Object { ([Byte]$_) -65 }

To turn this into a bit mask, use the Pow() function:

$driveList = 'a', 'b:', 'd', 'Z', 'x:'

$DriveList |
    ForEach-Object { $_.toUpper()[0] } |
    Sort-Object |
    ForEach-Object { [Math]::Pow(2,(([Byte]$_) -65)) }