Task

Write a function/procedure/subroutine that is called with an integer value and returns the middle three digits of the integer if possible or a clear indication of an error if this is not possible.

Note: The order of the middle digits should be preserved.

Your function should be tested with the following values; the first line should return valid answers, those of the second line should return clear indications of an error:

123, 12345, 1234567, 987654321, 10001, -10001, -123, -100, 100, -12345
1, 2, -1, -10, 2002, -2002, 0

Show your output on this page.




#!/bin/awk -f
# use as: awk -f middle_three_digits.awk
 
BEGIN {
	n = split("123 12345 1234567 987654321 10001 -10001 -123 -100 100 -12345 1 2 -1 -10 2002 -2002 0", arr)
 
	for (i=1; i<=n; i++) {
		if (arr[i] !~ /^-?[0-9]+$/) {
			printf("%10s : invalid input: not a number\n", arr[i])
			continue
		}
 
		num = arr[i]<0 ? -arr[i]:arr[i]
		len = length(num)
 
		if (len < 3) {
			printf("%10s : invalid input: too few digits\n", arr[i])
			continue
		}
 
		if (len % 2 == 0) {
			printf("%10s : invalid input: even number of digits\n", arr[i])
			continue
		}
 
		printf("%10s : %s\n", arr[i], substr(num, len/2, 3))
	}
}
 