Perl数值变量

Question

Perl和我不同意变量是否是数字。我错了，当然，但是为什么？

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.。

它，其实，数字为可当我使用

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

其设置字符串Downloaded: 3.09680080413818 MB看到。

编辑：啊，愚蠢的错误，感谢你抓住它。

Answer 1

您需要的变量印记：

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

看起来你可能是指：

比

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

等这应该工作。