perl文件以十六进制数字82表示？

Question

Trying to do binary to hex conversion on a file. I can output the hex but however when I try to output the result to a file,variable it returns the string "82". I cannot understand why; like all things most likely something simple.

#!/usr/bin/perl -w

use strict;

my $blockSize = 1024;
my $fileName = $ARGV[0];
my $hexName = $ARGV[1];
open(F,"<$fileName") or die("Unable to open file $fileName, $!");
binmode(F);
my $buf;
my $ct=0;

while(read(F,$buf,$blockSize,$ct*$blockSize)){
    foreach(split(//, $buf)){
    printf unpack ("H*", $_);    #prints the hex stream to terminal just fine
    open(H,">$hexName") or die("Unable to open file $fname, $!");
    binmode (H);
        printf H unpack ("H*", $_);
    close (H);

    }
    print "\n";
    $ct++;
}
close(F);

Output

perl rawrHexFile.pl test.png file.hex
89504e470d0a1a0a0000000....

mookie@temple:/srv/bench % cat file.hex 82

cat file.hex
82

Thanks.

Here's my final code which works. in case of

use strict;
my $fileName = $ARGV[0];
my $hexName = $ARGV[1];
my $hexCodeFile = $ARGV[2];
my $hexDecodeFile = $ARGV[3];
my $blockSize = -s $fileName;
my $buf;

open(F,"<$fileName") or die("Unable to open file $fileName, $!");
binmode(F);

open(H,">$hexName") or die("Unable to open file $hexName, $!");
read(F,$buf,$blockSize);
        print H unpack ("H*", $buf);
close (H);
close(F);

Answer 1

You recreate the file (open >) for each byte of the input file, so you only get the output for the last byte of the input file. Open the file outside of the loop.

Also, you keep appending to $buf rather than replacing its content, so your output will look like AABABCABCDABCDE instead of the desired ABCDE (where each letter represents the output for 1024 bytes of input)

Fixed:

use strict;
use warnings qw( all );

use constant BLOCK_SIZE => 64*1024;

my ($in_qfn, $out_qfn) = @ARGS;

open(my $in_fh, '<:raw', $in_qfn)
   or die("Unable to open \"$in_qfn\": $!\n");
open(my $out_fh, '>', $out_qfn)
   or die("Unable to open \"$out_qfn\": $!\n");

while (1) {
    defined( my $rv = sysread($in_fh, my $buf, BLOCK_SIZE) )
       or die("Unable to read from \"$in_qfn\": $!\n");

    last if !$rv;

    print($fh_out unpack("H*", $buf))
       or die("Unable to write to \"$out_qfn\": $!\n");
}

close($fh_in);
close($fh_out)
   or die("Unable to write to \"$out_qfn\": $!\n");

The above addressed a lot of other issues in your program:

• Use of 2-arg open
• Use of printf without a pattern
• Needless use of global vars
• Needlessly splitting the input when unpack H* handles strings of any length
• Inefficient 1 KiB reads when Perl reads from the OS in 4 KiB or 8 KiB chunks
• Use of binmode for a text file