Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

I am trying to get this to print out my entry in reverse order. It works fine except I have to hit <Ctrl> zafter my last input and then it shows my reversed printout. I want it to allow me to enter the word 'done' after my last input and then show me the results. Here is my attempt:
 print "Enter your data and then it will print out in reverse order.\n
+";

 @input = <stdin>;
 chop (@input);

 $currentline = 1;
 while($currentline <= @input)
 {
  @words=split(/ /,$input[$currentline - 1]);
  #@words=reverse(@words);
  $input[$currentline - 1]=join(" ",@words,"\n");
  last if $input eq 'done';
  $currentline++;
 }

 @input=reverse(@input);
 print(@input);

[download]

Replies are listed 'Best First'.
Re: Ending user input
by broquaint (Abbot) on May 28, 2002 at 12:46 UTC
    Try reading the input in a loop e.g 
    my @input;
while(<STDIN>) {
    chomp;
    last if $_ eq 'done';
    push @input, $_;
}
print join $/, reverse @input;

    [download]
    Also use chomp() instead of chop() as it does what you mean (which is remove the newline ending (which is system dependent (hence the use of $/ in the join() (gee, is this sounding a little Lispish? (Never mind)))))[1].
    HTH

    _________
    broquaint

    [1] shamelessly lifted from perlsub ;-)

[reply]
[d/l]
      thank you
[reply]
Re: Ending user input
by vladb (Vicar) on May 28, 2002 at 12:55 UTC
    To stop asking for more user input after the word 'done' has been entered, you may simply put <STDIN> inside a loop containing also a conditional (for exit): 
    use strict; # never go by without it! ;)

rint "Enter your data and then it will print out in reverse order.\n";

 my @input;
 while (<STDIN>){
   chomp; 
   last if m/done/i;  # quit this loop if input 
                      # matches (case insensitive) the word 'done'.
   push @input, $_;   # otherwise, add the word to the list
 }

 # Use 'for' loop instead of while if you need to
 # access array elements via an index variable.
 for (my $currentline = 1; $currentline <= scalar @input; $currentline
+++)
 {
  my @words=split(/ /,$input[$currentline - 1]);
  #@words=reverse(@words);
  $input[$currentline - 1]=join(" ",@words,"\n");
 }

 @input=reverse(@input);
 print(@input);

    [download]

    UPDATE: polished your code a little bit. Please, take a look at the in-line comments provided ;).

    UPDATE 1: Ooops, accidentally pasted a line of code I used to test my way of 'thinking' (with the 'perl -e' command): 
    while(<STDIN>){chomp;last if m/done/i;push @a, $_;}print@a;

    [download]
    Sorry about that, Anonymous Monk! ;)

    _____________________ 
    $"=q;grep;;$,=q"grep";for(`find . -name ".saves*~"`){s;$/;;;/(.*-(\d+)
+-.*)$/;
$_=["ps -e -o pid | "," $2 | "," -v "," "];`@$_`?{print"+ $1"}:{print"
+- $1"}&&`rm $1`;
print$\;}

    [download]
[reply]
[d/l]
[select]
      thanks for info. I tried your script and got an error message with "@a". What does the explicit package name refer to in this error message? 
      Global symbol "@a" requires explicit package name at C:\Perl\bin\EnRev
+er.pl line
 3.

      [download]
[reply]
[d/l]
        Hi.

        You need to precede the '@a' array with 'my'.
        You could define it above the main code section or as needed:
        my @a = qw( 1 2 3 );

        [download]


        -Katie.
[reply]
[d/l]

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