Perl数字变量

Question

Perl和我不同意变量是否是数字。我当然错了，但为什么呢？

my $bytes = 0;
# . . .
$bytes = $bytes + length($text);
# . . .
my $MB = $bytes / 1048576;
my $string = sprintf("Downloaded: %.1f MB\n", MB);

给出Argument "MB" isn't numeric in sprintf at foo.pl line 200.。

事实上，这是我使用

时可以看到的数字

my $string = "Downloaded: $MB MB\n";

将字符串设置为Downloaded: 3.09680080413818 MB。

编辑：啊，愚蠢的错误，谢谢你抓住它。

Answer 1

你需要变量sigil：

my $bytes = 0;
# . . .
$bytes = $bytes + length($text);
# . . .
my $MB = $bytes / 1048576;
my $string = sprintf("Downloaded: %.1f MB\n", $MB);   # <--- note the $MB at the end

Answer 2

看起来你可能意味着：

my $string = sprintf("Downloaded: %.1f MB\n", $MB);

除此之外，这应该有用。