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Top Forums UNIX for Beginners Questions & Answers Noob question: How to check the total number of inputs entered by user? Post 303042047 by wisecracker on Thursday 12th of December 2019 08:26:43 AM
Old 12-12-2019
Hi jejemonx...
This is what vbe was referring to assuming you are using 'bash':
Code:
Last login: Thu Dec 12 13:15:18 on ttys000
AMIGA:amiga~> bash --version
GNU bash, version 3.2.57(1)-release (x86_64-apple-darwin18)
Copyright (C) 2007 Free Software Foundation, Inc.
AMIGA:amiga~> 
AMIGA:amiga~> 
AMIGA:amiga~> help read
read: read [-ers] [-u fd] [-t timeout] [-p prompt] [-a array] [-n nchars] [-d delim] [name ...]
    One line is read from the standard input, or from file descriptor FD if the
    -u option is supplied, and the first word is assigned to the first NAME,
    the second word to the second NAME, and so on, with leftover words assigned
    to the last NAME.  Only the characters found in $IFS are recognized as word
    delimiters.  If no NAMEs are supplied, the line read is stored in the REPLY
    variable.  If the -r option is given, this signifies `raw' input, and
    backslash escaping is disabled.  The -d option causes read to continue
    until the first character of DELIM is read, rather than newline.  If the -p
    option is supplied, the string PROMPT is output without a trailing newline
    before attempting to read.  If -a is supplied, the words read are assigned
    to sequential indices of ARRAY, starting at zero.  If -e is supplied and
    the shell is interactive, readline is used to obtain the line.  If -n is
    supplied with a non-zero NCHARS argument, read returns after NCHARS
    characters have been read.  The -s option causes input coming from a
    terminal to not be echoed.
    
    The -t option causes read to time out and return failure if a complete line
    of input is not read within TIMEOUT seconds.  If the TMOUT variable is set,
    its value is the default timeout.  The return code is zero, unless end-of-file
    is encountered, read times out, or an invalid file descriptor is supplied as
    the argument to -u.
readonly: readonly [-af] [name[=value] ...] or readonly -p
    The given NAMEs are marked readonly and the values of these NAMEs may
    not be changed by subsequent assignment.  If the -f option is given,
    then functions corresponding to the NAMEs are so marked.  If no
    arguments are given, or if `-p' is given, a list of all readonly names
    is printed.  The `-a' option means to treat each NAME as
    an array variable.  An argument of `--' disables further option
    processing.
AMIGA:amiga~> _

AND, an example of how it works:
Code:
Last login: Thu Dec 12 13:15:49 on ttys000
AMIGA:amiga~> read a b c
1
AMIGA:amiga~> echo "${a} ${b} ${c}"
1  
AMIGA:amiga~> read a b c
1 2
AMIGA:amiga~> echo "${a} ${b} ${c}"
1 2 
AMIGA:amiga~> read a b c
1 2 3
AMIGA:amiga~> echo "${a} ${b} ${c}"
1 2 3
AMIGA:amiga~> _

As you can see whether you input variables 'b' and 'c' or not they have 'NULL' values so there will always be 3 variables.
You could always use 3 separate 'read's and check each one for validity and restart the loop as required if one or more is not a number...
 

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CheckDigits::M09_001(3pm)				User Contributed Perl Documentation				 CheckDigits::M09_001(3pm)

NAME
CheckDigits::M09_001 - compute check digits for Euro notes SYNOPSIS
use Algorithm::CheckDigits; $euro = CheckDigits('euronote'); if ($euro->is_valid('X07738250357')) { # do something } $cn = $euro->complete('X0773825035'); # $cn = 'X07738250357' $cd = $euro->checkdigit('X07738250357'); # $cd = '7' $bn = $euro->basenumber('X07738250357'); # $bn = 'X0773825035' DESCRIPTION
ALGORITHM 1. Letters are replaced with their position in the alphabet ('A' = 1, ...). 2. The total of the digits of all numbers is computed. 3. This sum is taken modulo 9. 4. The check digit is the difference between 8 and the number of step 3. To validate the last digit of the total of the digits of all numbers inclusive check digit must be 8. METHODS is_valid($number) Returns true only if $number consists solely of numbers and the last digit is a valid check digit according to the algorithm given above. Returns false otherwise, complete($number) The check digit for $number is computed and concatenated to the end of $number. Returns the complete number with check digit or '' if $number does not consist solely of digits. basenumber($number) Returns the basenumber of $number if $number has a valid check digit. Return '' otherwise. checkdigit($number) Returns the checkdigit of $number if $number has a valid check digit. Return '' otherwise. EXPORT None by default. AUTHOR
Mathias Weidner, <mathias@weidner.in-bad-schmiedeberg.de> SEE ALSO
perl, CheckDigits, www.pruefziffernberechnung.de. perl v5.10.0 2008-05-17 CheckDigits::M09_001(3pm)
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