Driver code
$ s = "45" ; echo primeDigits ( $ s ) . " STRNEWLINE " ; $ s = "1000" ; echo primeDigits ( $ s ) . " STRNEWLINE " ; $ s = "7721" ; echo primeDigits ( $ s ) . " STRNEWLINE " ; $ s = "7221" ; echo primeDigits ( $ s ) . " STRNEWLINE " ; $ s = "74545678912345689748593275897894708927680" ; echo primeDigits ( $ s ) ; ? >