wordlist.pl第11行的perl语法错误,靠近")$ fh"

Question

my $fn= "words.txt";
open ($fn), $file;
if (! -e "$fh") $fh="STDIN";
while (<$fn>){;
    my $total_words = @words; #All word count
    my %count;
    $count{$_}++ for @words; # Here are the counts
    my $uniq_words  = scalar keys %count; # Number of uniq words
}
# Print sorted by frequency

print "$_\t$count{$_}" for (sort { $count{$b} <=> $count{$a} } keys %count);

close FILE;
exit 0

我收到这个错误:

Scalar found where operator expected at wordlist.pl line 8, near ") $fh"
        (Missing operator before $fh?)
syntax error at wordlist.pl line 8, near ") $fh"
Execution of wordlist.pl aborted due to compilation errors.

请帮忙

Answer 1

在条件之后,Perl 总是需要在代码周围使用大括号:

你写了:

if (! -e "$fh") $fh="STDIN";

你应该写:

if (! -e "$fh") { $fh="STDIN"; }

要么:

$fh = "STDIN" if ! -e "$fh";

这些在语法上是正确的.但是,代码在语义上被打成碎片.要打开文件,请使用:

open my $fh, '<', $fn or die "Failed to open $fn";

并始终使用use strict;和use warnings;.Perl专家使用它们来确保它们没有犯下愚蠢的错误.新手也应该​​这样做.