looping doubt

[divyashree]

I am writing a script in bash.
In this the user will input a month name in Jan, Feb format. All the 12 months are stored in an array.

I want to check if the user enter correct month name and then it will match a value in the array and go out of the loop to execute something. If donot match then it exit with a message.

[kurtdriver]

Maybe you can post what you've got so far?

[three18ti]

>>then it will match a value in the array
hmmm... sounds to me like you are using a hash?

Because:

#!/usr/bin/perl
my @months = qw(Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec);
print $months[2] . "\n";
-------------------
Mar

However,

#!/usr/bin/perl
my %months = (
   Jan  => 5,
   Feb  => 7,
   Mar  => 3,
   Apr  => 4,
   May => 1,
   Jun  => 88,
   Jul   => 23,
   Aug => 15,
   Sep  => 533,
   Oct  => 123,
   Nov => 1233,
   Dec  => 2,
);
print $months{'Jul'} . "\n";
------------------------------
23

Since you are need to evaluate a month as a value, a hash would be more useful than an array as you can parse the hash for existing keys, vs using an array which you will have to iterate through the array for every existing value.

you may assign a value to each key manually or you can build the hash pragmatically. for my example I will assume the months are keyd to their value. (since this appears to be input validation I am recommending this method, there are many other, better ways to deal with dates)

first for the array example (this turned out to be rather c like...):

#!/usr/bin/perl
#
# program takes one argument from the command line,
# iterates through the array of months, and verifies the users input
# 
# can easily be modified to take input into a variable via:
# my $input = <STDIN>;

use strict;
use warnings;

my $input = $ARGV[0];
my @months = qw(Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec);

my $exists = -1;
for (my $i = 0; $i < $#months + 1; $i++) {
  if ($months[$i] eq $input){
     $exists = $i;
     last;
  }
}

if ($exists >= 0){
  print "Input exists at $exists in \@months \n";
}
else {
  print "Input does not exist";
}

now for the hash example:

# program takes one argument from the command line,
# iterates through the array of months, in the real world I assume
# the programer is going to assign specific values to the months and will use
# some sort of case statement? 
# 
# can easily be modified to take input into a variable via:
# my $input = <STDIN>;

use strict;
use warnings;


# I'm building my hash here because I'm lazzy...  I'm assuming the end product will
# have specific key/value pairs...
# written less perly for clarity
my %months;
my @months = qw(Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec);
foreach (@months){
    $months{$_} = int rand 1000;
}

my $input = $ARGV[0];

if ($months{$input}){
    print "Entered correct Name.  $input => $months{$input}";
}
else  {
    print "$input is not a valid month";
}

Don't really know bash, hence the Perl.

[drl]

Hi.

Using bash:

#!/usr/bin/env bash

# @(#) s1	Demonstrate search for item in array, shell.

# Utility functions: print-as-echo, print-line-with-visual-space, debug.
pe() { for i;do printf "%s" "$i";done; printf "\n"; }
pl() { pe;pe "-----" ;pe "$*"; }
db() { ( printf " db, ";for i;do printf "%s" "$i";done; printf "\n" ) >&2 ; }
db() { : ; }
C=$HOME/bin/context && [ -f $C ] && $C 

m=( jan feb mar apr may jun jul aug sep oct nov dec end )
last=$(( ${#m[*]}-1 ))
db " Index of last slot is $last."

month=${1?" Must supply month to be searched for."}
db " Searching for :$month:"

pl " Results:"
m[$last]=$month
i=0
while [ ${m[$i]} != $month ] 
do
  (( i++ ))
done

if [ $i == $last ]
then
  pe " No such month as \"$month\""
else
  pe " Found \"$month\" at $i";fi
fi

exit 0

producing for a month not found:

% ./s1 xx

Environment: LC_ALL = C, LANG = C
(Versions displayed with local utility "version")
Oker|relrel, machine: Linux, 2.6.26-2-amd64, x86_64
Distribution        : Debian GNU/Linux 5.0.8 (lenny) 
GNU bash 3.2.39

-----
 Results:
 No such month as "xx"

and for the last month in the array:

% ./s1 dec

Environment: LC_ALL = C, LANG = C
(Versions displayed with local utility "version")
Oker|relrel, machine: Linux, 2.6.26-2-amd64, x86_64
Distribution        : Debian GNU/Linux 5.0.8 (lenny) 
GNU bash 3.2.39

-----
 Results:
 Found "dec" at 11

Best wishes ... cheers, drl

[divyashree]

#/bin/bash



#set -x




echo "Enter the month:"
read month

#echo "Enter the date:"
#read date


declare -a monarr=( Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec )


len=${#monarr[@]}

#for i  in "${monarr[@]}"

  for (( i = 0 ; i < $len ; i++ ))
  do
   if [ $month  != ${monarr[$i]} ]
    then
      echo "Please enter the correct month"

     else
     break
  
    fi
  done

echo "Month:$month  Date:$date"

This is what I have..