webchem (version 0.0.5.0)

is.cas: Check if input is a valid CAS

Description

This function checks if a string is a valid CAS registry number. A valid CAS is 1) separated by two hyphes into three parts; 2) the first part consists from two up to seven digits; 3) the second of two digits; 4) the third of one digit (check digit); 5) the check digits corresponds the checksum. The checksum is found by taking the last digit (excluding the check digit) multiplyingit with 1, the second last multiplied with 2, the third-last multiplied with 3 etc. The modulo 10 of the sum of these is the checksum.

Usage

is.cas(x, verbose = TRUE)

Arguments

x

character; input CAS

verbose

logical; print messages during processing to console?

Value

• a logical

Examples

is.cas('64-17-5')
is.cas('64175')
is.cas('4-17-5')
is.cas('64-177-6')
is.cas('64-17-55')
is.cas('64-17-6')