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How to compare strings OR chars of 2 strings

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bruceleung2000

bruceleung2000

IS-IT--Management
Dec 20, 2003
19
HK
Hello ALL,
I am a newbie to perl programming. I am trying to compare 2 strings read from separate files. It seems it the results are the same - cannot compare 2 same strings.

Can anyone tell me how to correct the following programs ?

=====
open (fh0, $fname0) or die "cannot read file $fname0" ; # $_[0] is first argument in the function
open (fh1, $fname1) or die "cannot read file $fname1" ;

sysread fh0, $instr0, $MAX_READ;

sysread fh1, $instr1, $MAX_READ;

if ( $instr0 =~ $instr1 ) { # ??????
print "eqqqqq char \n" ;
close fh0;
close fh1;
return $TRUE;
} # endif
close fh0;
close fh1;
print "NOTTTTTTTTT EQ char \n" ;
return $FALSE;
==================================
 
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You want to check if the strings are the same right?
Code: 
if ( $instr0 eq $instr1 ) {
   # do something
}
Use "eq" to compare strings, or "==" to compare numbers.
 
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I used EQ before, but it seems not working well.

Regards,
Bruce
 
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[MORE INFO for my problem]

It always NOT equal and also hits some strange error as follows :
=========================================
444444444]instr0=[111111111111xxxxxxx1111111111111111111111111111111111111111111
11111111111111111
222222222222222
3333333333333333333333333333333333333333
4444444444]
instr1=[111111111111111111111111111111111111111111111111111111111111111111111111

2222222yyyyyyyy22222222
3333333333333333333333333333333333333333
444444444]
NOTTTTTTTTT EQ char
inside for loop IIIII
i=[3]

G:\Schedule_Jobs\appletemp>perl ok2.pl *.html > ok3.out
Use of uninitialized value in print at ok2.pl line 62.
Use of uninitialized value in print at ok2.pl line 66.
Unmatched [ in regex; marked by <-- HERE in m/<HTML> ?????
<BODY>
<HEAD> Ver 4.1 developed by Bruce Leung on 27 July 2003 <BR> </HEAD>
??? <-- HERE ??????<BR>
????????????????????/ at ok2.pl line 42.

======================

Regards,
Bruce
 
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Assuming your files are text files, 'eq' (not 'EQ' - case is important) will work OK. To test, try setting $fname0 and $fname1 to the same filename, in which case your two strings will definitely be equal.
 
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What's on line 42, where the error is occurring?
 
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Sorry you are right - my mistake.

BTW, how can I
1) read strings from a file in a posstion relative to END of file
2) read a line instead of fixed number of chars

Regards,
Bruce
 
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Reading from the end of a file is dealt with in this node on perlmonks

To read a single line:
Code: 
my $line = <fh0>;
To continually read lines in a loop:
Code: 
while( my $line = <fh0>) {
   # do something
}

#or

while (<fh0>) {
   # the line is now in the $_ variable
}
 
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Hello,
What I want is :
1) to skip frist 5 lines for the 2 following files (fh0 and fh1) and need to mix with function (sysread) to read before the sysread buffer.


============================================
open (fh0, $fname0) or die "cannot read file $fname0" ;
open (fh1, $fname1) or die "cannot read file $fname1" ;
??? how to skip 1st 5 lines for both files ???
sysread fh0, $instr0, $MAX_READ;
sysread fh1, $instr1, $MAX_READ;
================================================

Regards,
Bruce


 
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Hello ALL,
It would be best for me to locate the position from end of files (NOT begin) to compare the strings of files.

Regards,
Bruce
 
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You could read the whole file into an array with
Code: 
open (FH0, $fname0) or die "can't open $fname0";

my @file0 = (<FH0>);
chomp @file0; # remove trailing CRLFs
then you can just work backwards from the end of the array?
 
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That would work, but is inefficient for memory purposes as it slurps the whole file, as you said. The File::ReadBackwards achieves the same thing but is more memory-efficient.
 
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True, although it seems to be HTML of some sort. I guess if it's small enough to display in someone's browser, it's not going to be too much of a hog...
 
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