perl string match issue

knockout_artist · 01-06-2009, 11:13 AM

Hi every one,

Code:

#!/usr/bin/perl 

open FILE, "<", "test-last" or die $!;


while (<FILE>) {

$test= $_;  //current line become $test

@names=qw( one two three four );    //aray to hold few values

foreach  $names(@names){
print " $test";  print "$names";   // now here it matches!! i mean string from file and from //aray

if($test eq $names){

print "match found \n";   //doenst print a thing

}

test-last

Code:

five
six
two
seven

See "two" should print "match found" but it doesn't.

Any ideas?

Thanks

angrek · 01-06-2009, 12:06 PM

You left out two ending brackets when you pasted your code btw.

If you put a

Code:

print "Length of test is " . length($test) . "\n";

in your code you'll notice that it's one character longer than the actual length of your $test variable that you're pulling from the file. You're pulling a newline character. After your foreach line add a

Code:

chomp($test);

and it should work fine.

mk27 · 01-06-2009, 12:13 PM

That's because the lines from the file have a newline at the end, whereas the ones in your array do not. Use chomp to remove it:

Code:

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

my @names=qw( one two three four );    # no need to redeclare this each time in the loop!

while (<DATA>) {
	my $test=$_;
	chomp $test;	# removes newline
	foreach  $name(@names){
		print "\"$test\" \"$name\"\n"; # using escaped quotes you could have seen this  
		if($test eq $name) {print "MATCH FOUND!\n"}
	}
}

__DATA__
five
six
two

You can read in data from the end of a script this way the same as if it were in a file. Using the escaped quotes in your original version you would have seen this:

"five
" "one"
"five
" "two"

"perlmonks" is a good and very active forum for perl help.

ps. why did you use c-style comments?

knockout_artist · 01-06-2009, 12:32 PM

Quote:

Originally Posted by mk27

ps. why did you use c-style comments?

I am deeply in love with C

, . the first language I learned second would be perl.
I love playing on hardware level with C. Its awesome

knockout_artist · 01-06-2009, 01:50 PM

Thank you very much both of you,
mk27 thanks for pointing out loop thingie.

knockout_artist · 01-06-2009, 02:03 PM

Good time to ask an old question

Code:

my @names=qw( one two three four );    # no need to redeclare this each time in the loop!

while (<DATA>) {
	my $test=$_;

why did you use "my" before declaring array and variable ?

Thanks

angrek · 01-06-2009, 02:11 PM

Quote:

Originally Posted by knockout_artist

Thank you very much both of you,
mk27 thanks for pointing out loop thingie.

Yeah, sorry about that... didn't mean to put it in the loop there.

chrism01 · 01-06-2009, 06:43 PM

@knockout-artist; ALL perl programs should start with

Code:

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

which will warn you about syntax errors and dodgy code usage. Never code without them

An alternative to '-w' is 'use warnings;'

Also, if you want to do a test compile without running the prog, use

perl -wc prog.pl

If you 'use strict;' then you have to declare your vars using 'my', which restricts their scope to the current block (usually current subroutine). IOW, avoid globals as much as possible.
Think C (also my main lang prev to Perl).

Good Perl links:
http://perldoc.perl.org/
http://www.perlmonks.org/?node=Tutorials

knockout_artist · 01-13-2009, 11:45 AM

Code:

 
#!/usr/bin/perl 
use strict;

my $flag =0 ;      #used to flags
my $flag2 =0;
my @names=qw(  ); #empty array
my $i=0;          # mostly for debugging
my $j=0;          #same as above 
my $test;          #hold value from __DATA__

while(<DATA>)    #read all 4 valuse from  DATA
{
print "$flag Flag at start\n";   #debugging
my $test=$_;
chomp($test);

if ($j==0 ){                   #add first value in the array so in next loop it would have some thing to look at
print "push $test into names array\n";
  push (@names, "$test" );
  }
print "name from DATA $test\n";    #debug   print value read from data

foreach my $names(@names){           #inner loop  for @names array
print " Test==$test Names==$names \n";     #debug
if($test eq $names){                       #make sure that if it already exist
$flag = 2;                                   #playing with those to flags

$flag2 =1;

}else{

$flag =0 ;
}
if ($flag != 2 ){

$flag = 0;

}

}
print " test = $test  flag = $flag   \n";
$j++;
if($flag ==0){
push (@names, "$test" );      #Tried differnt flag

}
print "flag2 $flag2\n";
}
$flag2 =0;
print "@names\n";

__DATA__
one
one
three
one

What I need is out put
[qoute]one three[/quote]

what I get is

Quote:

one three one

output ::

Code:

  ./last-log2.pl 
0 Flag at start
push one into names array
name from DATA one
 Test==one Names==one 
 test = one  flag = 2   
flag2 1
2 Flag at start
name from DATA one
 Test==one Names==one 
 test = one  flag = 2   
flag2 1
2 Flag at start
name from DATA three
 Test==three Names==one 
 test = three  flag = 0   
flag2 1
0 Flag at start
name from DATA one
 Test==one Names==one 
 Test==one Names==three 
 test = one  flag = 0   
flag2 1
one three one   ## print whats inside the array

Any ideas?
Thanks!

knockout_artist · 01-13-2009, 02:55 PM

BTW

I was able to resolve it.
I will post the code tomorrow.

Thank you every one. :-)

chrism01 · 01-13-2009, 05:48 PM

Don't forget the -w switch (or 'use warnings').

I'd also change

while(<DATA>)

to

while( defined($test = <DATA>) )

removing need for

my $test=$_;

Try indenting your code as well, its easier to read...

GaijinPunch · 01-13-2009, 05:53 PM

Seconded on warnings & strict.
My Perl places will tell you to put those in and run your code again before bothering to help... although I don't think they would've helped here.