initial commit

bash/armstrong-numbers/armstrong_numbers.sh

@@ -0,0 +1,44 @@
+#!/usr/bin/env bash
+
+# set to mask to enable logs. 0: none, 255: all
+(( DEBUG=2#00000000 ))
+
+# $1: log level (mask), then strings to display.
+debug () {
+    (( DEBUG & $1 )) && shift && echo "${@}" >&2
+}
+
+usage () {
+    echo "usage: ./armstrong_numbers.sh <number>" >&2
+    exit 1
+}
+
+# basic args checks: 1 arg, digits  (at least 1) only
+(( $# != 1)) || [[ ! "$1" =~ ^[[:digit:]]+$ ]] && usage
+
+number="$1"
+digits=${#number}
+armstrong=0
+result="false"
+
+debug 1 d=$digits n=$number
+
+# armstrong number calculation
+for (( i=0; i<digits; ++i )); do
+    ((armstrong += ${number:$i:1} ** digits ))
+done
+
+debug 2 "armstrong=$armstrong"
+
+((number == armstrong)) && result="true"
+
+echo "$result"
+
+exit 0
+
+# Indent style for emacs
+# Local Variables:
+# sh-basic-offset: 4
+# indent-tabs-mode: nil
+# comment-column: 60
+# End: