Question

有谁知道如何将两个字节从文件转换为一个字节？我试图将两个字节读入数组的每个元素，然后将其除以6553，将时间除以255，以转换为一个字节。然而，这不起作用。有什么建议吗？

open my $fh, '<:raw', $test;
my @info = do {
    local $/ = \2;
    <$fh>;
};
close($fh);

foreach(@info){
    $_= (($_)/65535)*255;
}
my $temp = "temp.txt";

open(TEMP, ">", $temp);
print TEMP my $info;
close(TEMP);

错误：

Argument "\0^B" isn't numeric in division (/) at ./con.pl line 33.
Argument "^A^B" isn't numeric in division (/) at ./con.pl line 33.
Argument "^B^B" isn't numeric in division (/) at ./con.pl line 33.
Argument "^E^B" isn't numeric in division (/) at ./con.pl line 33.
Argument "^G^B" isn't numeric in division (/) at ./con.pl line 33.
Argument "^H^B" isn't numeric in division (/) at ./con.pl line 33.
Argument "^G^B" isn't numeric in division (/) at ./con.pl line 33.

Answer 1

如果字节来自文件，请将它们转换为数字。这就是unpack的用途：

$c = "\x1\x2";
print unpack 'n', $c;

输出：258。

使用pack将数字转换回字节。

Answer 2

pack 'C', unpack 'n', $twobytes;            # Big-endian input
pack 'C', unpack 'v', $twobytes;            # Little-endian input
pack 'C*', unpack 'n*', $many_byte_pairs;   # Big-endian input
pack 'C*', unpack 'v*', $many_byte_pairs;   # Little-endian input

检查是否有溢出。

Perl将short转换为一个字节

2 个答案: