DIZtools (version 1.0.3)

test_check_digit: Validate an ID Using the Check Digit (DIN ISO 7064, Mod 11,10)

Description

This function verifies whether a given ID is valid by checking its check digit using the DIN ISO 7064, Mod 11,10 algorithm.

Usage

test_check_digit(test)

Value

A logical value: `TRUE` if the check digit is correct, `FALSE` otherwise. Returns `FALSE` with an error message if the input format is invalid.

Arguments

test

A numeric or character string representing the ID. It should be exactly 10 digits long, including the check digit.

Details

The function processes the input as follows: - If the input has 10 digits and does not start with `0`, it is assumed to be a ID with a check digit. - If the input has 10 digits and starts with `0`, it is considered an old ID without a check digit, and validation cannot be performed. - If the input has 9 digits, it lacks a check digit, so validation is not possible. - If the input format is invalid, an error message is generated.

The function extracts the main ID (without the check digit), computes the expected check digit using `calculate_check_digit()`, and compares it with the provided check digit.

Examples

test_check_digit("1000001381")  # Returns TRUE if the check digit is correct
test_check_digit("1000001121")  # Another valid ID
test_check_digit("1007002482")  # Returns FALSE if the check digit is incorrect