[powershell] how do I loop through a line from a csv file in powershell

I want to process a csv file in powershell, but I don't know what the column headings in the CSV file will be when it is processed.

For example:

$path = "d:\scratch\export.csv"
$csv = Import-csv -path $path

foreach($line in $csv)
{ 
    foreach ($head in $line | get-member | where-object {$_.MemberType -eq "NoteProperty"} | select Definition)
    {
        #pseudocode...
        doSomething($head.columnName, $head.value)
    }

}

How do I loop through the line in the csv file, getting the name of the column and the value? Or is there another way I should be doing this (like not using Import-csv)?

A slightly other way of iterating through each column of each line of a CSV-file would be

$path = "d:\scratch\export.csv"
$csv = Import-Csv -path $path

foreach($line in $csv)
{ 
    $properties = $line | Get-Member -MemberType Properties
    for($i=0; $i -lt $properties.Count;$i++)
    {
        $column = $properties[$i]
        $columnvalue = $line | Select -ExpandProperty $column.Name

        # doSomething $column.Name $columnvalue 
        # doSomething $i $columnvalue 
    }
} 

so you have the choice: you can use either $column.Name to get the name of the column, or $i to get the number of the column

$header3 = @("Field_1","Field_2","Field_3","Field_4","Field_5")     

Import-Csv $fileName -Header $header3 -Delimiter "`t" | select -skip 3 | Foreach-Object {

    $record = $indexName 
    foreach ($property in $_.PSObject.Properties){

        #doSomething $property.Name, $property.Value

            if($property.Name -like '*TextWrittenAsNumber*'){

                $record = $record + "," + '"' + $property.Value + '"' 
            }
            else{
                $record = $record + "," + $property.Value 
            }                           
    }               

        $array.add($record) | out-null  
        #write-host $record                         
}