function to date formate into one to another

#******************************************************************************
# function to date formate into one to another
#******************************************************************************

function convertDateFormat($datetorev,$currentformat="ymd",$outputformat="dmy",$seperateby="/")
{
//This function is is not completed. the work remaining is adding more format conversions
if (( $currentformat=="ymd") and ($outputformat=="dmy"))
{
list($year, $month, $day) = split('[/.-]', $datetorev);
return $day.$seperateby.$month.$seperateby.$year;

}
else if (( $currentformat=="ymd") and ($outputformat=="mdy"))
{
list( $year,$month,$day) = split('[/.-]', $datetorev);
return $month.$seperateby.$day.$seperateby.$year;

}
else if (( $currentformat=="dmy") and ($outputformat=="ymd"))
{
list( $day,$month,$year) = split('[/.-]', $datetorev);
return $year.$seperateby.$month.$seperateby.$day;

}
else if (( $currentformat=="dmy") and ($outputformat=="mdy"))
{
list( $day,$month,$year) = split('[/.-]', $datetorev);
return $month.$seperateby.$day.$seperateby.$year;

}
else if (( $currentformat=="mdy") and ($outputformat=="ymd"))
{
list( $month,$day,$year) = split('[/.-]', $datetorev);
return $year.$seperateby.$month.$seperateby.$day;

}
else if (( $currentformat=="mdy") and ($outputformat=="dmy"))
{
list( $month,$day,$year) = split('[/.-]', $datetorev);
return $day.$seperateby.$month.$seperateby.$year;

}
else
{
return "Not valid";
}


}

#******************************************************************************