$MethodDefinition = @'
[DllImport("netapi32.dll", CharSet=CharSet.Unicode, CallingConvention=CallingConvention.StdCall,SetLastError=true )]
public static extern uint NetUserChangePassword (
    [MarshalAs(UnmanagedType.LPWStr)] string domainname,
    [MarshalAs(UnmanagedType.LPWStr)] string username,
    [MarshalAs(UnmanagedType.LPWStr)] string oldpassword,
    [MarshalAs(UnmanagedType.LPWStr)] string newpassword
);
'@
   
$NetAPI32 = Add-Type -MemberDefinition $MethodDefinition -Name 'NetAPI32' -Namespace 'Win32' -PassThru
function convert_sec_str {
        param([System.Security.SecureString]$str)
        $result = [System.Runtime.InteropServices.Marshal]::PtrToStringAuto([System.Runtime.InteropServices.Marshal]::SecureStringToBSTR($str))
        $result
}
function verify_new_pw {
        param( [System.Security.SecureString]$new, [System.Security.SecureString]$confirm )
        $new_conv = convert_sec_str $new
        $confirm_conv = convert_sec_str $confirm
        if ( $new_conv -eq  $confirm_conv ) {
                0
        } else {
                1
        }
}
 
function changepw {
    $domain = $( Read-Host "Domain")
    $username = $( Read-Host "Username")
    $oldP = $( Read-Host "Old password" -AsSecureString)
    $newP = $( Read-Host "New password" -AsSecureString)
    $confirm_P = $( Read-Host "Confirm New Password" -AsSecureString)
    
   if ( $( verify_new_pw $newP $confirm_P ) -eq 0 ) {
           $oldPassword = [System.Runtime.InteropServices.Marshal]::PtrToStringAuto([System.Runtime.InteropServices.Marshal]::SecureStringToBSTR($oldP))
            $newPassword = [System.Runtime.InteropServices.Marshal]::PtrToStringAuto([System.Runtime.InteropServices.Marshal]::SecureStringToBSTR($newP))
            $result = $NetAPI32::NetUserChangePassword($domain, $username, $oldPassword, $newPassword)
            echo "Result (should be 0): ${result}"
            Read-Host "Press Enter to exit"
            # exit 0
   } else {
            Write-Output "New password did not match confirmed password, exiting"
            Read-Host "Press enter to exit"
            # exit 1
    }      
}
changepw