i dont understand what you are trying to infer from that question.

I am not trying to infer anything :)

Your question as posted is unclear to me; esp your talk of the bytes pragma and vectors and widths ...

Have you read bytes?

If you could post some code in the style of perlintro , where you compare whatever value you have, with whatever value you expect, and show where you try to declare the "buffer size", it would clarify your question greatly for me

I am sorry about that. I have pasted the code i am trying out but i know it has a major flaw in it. Especially when i decalre $length_buffer, what i really want to say is that my $length_buffer is 32bytes wide i.e it can hold 256 bits. Anytime i read out an instrution address such as

0x405d75  
0x4035f7  
0x4035f8  
0x4035fb
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i compute its length and diplay it in bytes so i could use it for comparing the length of the address and the buffer in bytes. the source from where i picked up using the pragma Use bytes is below. (http://perlmeme.org/howtos/using_perl/length.html)

#!user/bin/perl
#use strict;
#use warnings;
use bytes;

$length_buffer= length(0x100) ;                                       
+             #buffer length
print "$length_buffer, \n";
$base=length(0x00);                                                   
+              #base address
print "$base, \n";

$base_end= ($base+ $length_buffer-1);                                 
+   #base_end address, here it means it goes from 0 to 255 which is 25
+6 elements in the buffer
print " The end of the buffer=$base_end, \n";                         
+   #just to check if the buffer end prints correctly, in this case it
+s 255


#$temp= 0xFFFFFFE0;
$count_hit=0;                                                         
+   #counter to calculate the number of hits
$count_miss=0;                                                        
+   #counter to calculate number of misses

################## Input and output Files#############################
+#######################################################

open(FILE1," < output_log.txt") or die "can't read the file";         
+   #trace file input
open(FILE2, "> o_hit_miss.txt") or die "can't write into the file";   
+   #output file containing the hit and miss informaiton


######################################################################
+#########################################################

while(<FILE1>){
    
    $inst_addr= $_;                                                  #
+ read the lines and store in in inst_addr
    #print " $inst_addr \n";                                          
+# to check if the inst_addr is being read out correctly from the give
+n file
    
###########################################calcultes the length of the
+ address and prints the same in bytes####################
    if($inst_addr) {
        
        #use bytes;                                               # Pr
+agma to display the string in bytes and not in characters
        
    #$len_ofinstr=length( $inst_addr);                                
+#calculates the length of string in bytes and assigns it to $len_inst
+r
    #print " Length in bytes: ", $len_ofinstr, "\n";                  
+#prints the length in bytes for my understanding

    
    if($len_ofinstr >= $base && $len_ofinstr <=$base_end) {
        
        #print" $hit, \n";
        #print FILE2 $hit. "\n";
        
        #print " The inst fits in the buffer->hit, \n";
        $len_ofinstr+=$len_ofinstr;
        #print "Total number of bytes in the buffer=", $len_ofinstr, "
+\n";
        
        $count_hit=$count_hit+1;
        #print " Number of hits in the buffer= $count_hit", "\n";
        print FILE2 "number of hits in buffer". $count_hit. "\n";
    }
}
    else{
        
        if($len_inst == $length_buffer) {
            
            print " it can not hold anymore, \n";
            $base= $instr_addr & 0xffffffe0;
        }
    }
}
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First off, uncomment strictures and fix the errors reported. At the very least, as your code stands, $len_ofinstr and $len_inst are used before they are assigned a value which is likely to be wrong.

What do you expect length to do?

What do you expect 'use bytes' to do? (The module's documentation says "use of this module for anything other than debugging purposes is strongly discouraged".)

Writing a test script of the form:

#!user/bin/perl
use warnings;
use strict;

my $inFile = <<FILE;
FILE

...

open my $fIn, '<', \$inFile;

while (defined (my $line = <$fIn>)) {
    ...
}
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and telling use what you expect as output would go a long way to making your issue clear to us. The open ... \$inFile; bit opens a string as a file which is a nice way of including sample data in your script while retaining the structure of file I/O of the full script.

Perl is the programming world's equivalent of English