perl 对二进制文件的操作

sub ChangeByte

{

my $file=shift();

my $Byte=shift();

my $value=shift();

open(FH,"+<$file") or die "File not exist \n";

binmode FH;

seek (FH,$Byte,0);

print (FH pack("H*",$value));

close(FH);

}

sub ChangeBit

{

my $file=shift();

my $Byte=shift();

my $Bit=shift();

#my $value1=shift(); 

open(FH,"+<$file") or die "File not exist \n";

binmode FH;

my $charb;

seek (FH,$Byte,0);

read(FH,$charb,1);

my $Bit2;

$Bit2=7-$Bit;

($charb)=unpack("B*",$charb);

       #print "the Byte is $charb";

my $chara=substr($charb,0,$Bit2);

my $value=substr($charb,$Bit2,1);

my $value1;

 

if ($value eq "1")

{

$value1="0";

}

else

{

$value1="1";

}

my $charc=substr($charb,$Bit2+1,$Bit);

$charb=$chara.$value1.$charc;

 

seek (FH,$Byte,0);

print (FH pack("B*",$charb));

close(FH);

}