search for '\' in perl

[kumeperl]

Hello Monks, i am new to perl programming. i am trying to write a program to find number of occurence of '\' in an array file path. I tried the follwing code,

  
@list = "C:\username\Sources"; 
  
foreach $arrchar (@list) 
{ 
   print "array char = $arrchar"; 
   if($_ = /\\/) 
               { 
                    print "\nfound one \n"; 
               } 
}

but it was not working, i mean it is not printng "found one". but errors = 0 please excuse my ignorance if my code is wrong. Reading the manual is confusing me further.. can anyone please help me with the code?

Thanks,

Kumeperl

[moritz]

There's no backslash in your string, which is why it doesn't find one. If you use warnings (as you should, especially as a beginner), it gives you a clue:

$ perl -wE 'say "C:\username\Sources"'
Unrecognized escape \S passed through at -e line 1.
C:SernameSources

The \ in the double-quoted strings have a special meaning. Use double backslash to in ""-literals to produce a backslash in the string.

[DStaal]

The line if($_ = /\\/) is probably not doing what you want it to do. Either you mean if($_ =~ m/\\/) which would mean "if it contains '\'", or you mean if($_ eq '\') which would mean "if it is '\'".

if($_ = /\\/) is attempting to assign something to $_, and testing if the assignment succeed. Probably not what you want.

[tinita]

please read perlintro, Modern Perl and/or one of the other tutorials. you're doing wrong almost everything what could possibly go wrong =)

you are not using warnings and strict.
the element in @List will contain the string "C:SernameSources".
you are trying to use $_ but $arrchar is the variable you want to do the matching on.
by saying $_ = /.../ you are assigning to $_. you have to say $arrchar =~ /\\/

[Lotus1]

Please add these to the top of your code:

use strict;
use warnings;

You are using doublequotes for the path so the backslash '\' is interpreted as an escape character for the next character. Try using single quotes. Also read perlretut, the perl regular expresion tutorial, especially the section about the 'g' modifier. Let us know what errors you get if you get stuck after trying these.

[ricDeez]

This is probably what you want, taking into account the comments by the other monks:

use strict;
use warnings;
use 5.012;
my @list = ("C:\\username\\Sources"); 
  
for (@list) 
{ 
   say "array char = $_"; 
   while ($_ =~ m/\\/g) 
       { 
        say "found a '$&'"; # holds the portion of the string that mat
+ched
    } 
}

[TJPride]

use strict;
use warnings;

open (HANDLE, 'C:\username\Sources') || die;
$_ = join '', <HANDLE>;
my @m = m/\\/g;    ### All matched strings
print ('Found ' . ($#m + 1) . ' matches!');

[kumeperl]

Hello monks, Thanks for your fast response. after taking your suggestions i did the following changes in code

#!/usr/bin/perl -w
 
use strict;
use warnings;

my $count;
my @list = 'C:\username\Sources';

chomp @list;
#print OUTPTR "$_\n" foreach @list;
foreach my $arrchar (@list)
{
   print "array char = $arrchar";
   if($arrchar =~ m/\\/)
               {
                    print "\nfound one \n";
                    $count += 1;
               }
   else
   {
      print"\n i am in else \n"
   }
}
print "value of count = $count";

the result is

array char = C:\username\Sources

found one

value of count = 1

i am expecting count = 2. again i am not sure why it is not working properly.

regards,

kumeperl

[Anonymous Monk]

perldoc://count occurrences

perldoc -q " count.*?occurrences "

perlfaq4#How can I count the number of occurrences of a substring within a string?

[TJPride]

I read that page a while ago, threw me off because the $count = (my pattern matching) format didn't seem to work. But apparently, $count = () = pattern match does, cool! I learn something new every day:

use strict;
use warnings;

open (HANDLE, 'C:\username\Sources') || die;
$_ = join '', <HANDLE>;
my $c = () = m/\\/g;
print "Found $c matches!";