CODEWITHSUNDEEP
perl
alyssamich
alyssamich

Reputation: 15

Reading from a File Based on a String Input

I'm writing a program currently in Perl, and what I want it to do is take the user's input (a string in my case), read a file, find an entry in the file with that input, and then print.

This is what I have so far in this particular subroutine where this bit of code is:

print "What is your Sun Sign?\n";
open ( my $sun, '<', 'sunsigns.txt' ) or die "I couldn't reach the file. Please try again.";
while (my $sun_out = <STDIN>) {
    if ($sun_out =~ /[\w$sun]/) {
        print $sun;
    }
}

When I do that, it gives me this:

GLOB(0x1db5f8)

I'm at my limit. I feel like I've literally tried everything that I've managed to Google. If anyone could at least point me in the right direction, please do.

Upvotes: 1

Views: 119

Answers (3)

brian d foy
brian d foy

Reputation: 132920

People have already answered the question about the task, but I'd like to point out why you got the output that you did.

First, you used the wrong variable in your print. Since $sun is a filehandle and that's the only argument you give to print, it outputs a text representation of that object. That's why you get the GLOB(...). I typically name all my handles with an h at the end. That's usually $fh for a file, $dh for a directory handle, and so on. That way these names stand out when I use them in the wrong place.

But, the various ways to call print is slightly annoying because print without any arguments uses the topic variable $_:

print; # outputs $_

Adding a filehandle as the first argument doesn't output $_ to that filehandle. I'm only slightly annoyed by this, but I get over it.

print $fh;  # GLOB(...)

You have to add the argument yourself, but without a comma between them (for reasons I leave out):

print $fh $_;

If you have that comma, your problem returns:

print $fh, $_;  GLOB(...)...

Upvotes: 2

toolic
toolic

Reputation: 62236

Here is a common way to do this in Perl.

First, get the input string from STDIN.

Then, open the input file and loop over all lines looking for the input string. When you find the string, print the full line containing the string.

use warnings;
use strict;

print "What is your Sun Sign?\n";
my $sun = <STDIN>;
chomp $sun;

open (my $fh, '<', 'sunsigns.txt') or die "I couldn't reach the file. Please try again.";
while (<$fh>) {
    if (/$sun/) {
        print;
    }
}

See also perlintro

Upvotes: 2

dawg
dawg

Reputation: 104092

Given this file:

$ cat file
♈ Aries (Ram): March 21–April 19.
♉ Taurus (Bull): April 20–May 20.
♊ Gemini (Twins): May 21–June 21.
♋ Cancer (Crab): June 22–July 22.
♌ Leo (Lion): July 23–August 22.
♍ Virgo (Virgin): August 23–September 22.
♎ Libra (Balance): September 23–October 23.
♏ Scorpius (Scorpion): October 24–November 21.

You can do something like this:

#!/usr/bin/perl

use strict; use warnings; 

print "Enter Sun Sign: ";
my $sign = <STDIN>;
chomp $sign;

open ( my $sun, '<', '/tmp/file' )or die "I couldn't reach the file. Please try again.";

while (my $line=<$sun>) {
    chomp $line;
    print $line if ($line=~/\b$sign\b/);
}

Test it:

Enter Sun Sign: Virgo
♍ Virgo (Virgin): August 23–September 22.

Upvotes: 1

Related Questions