Question

PERL语言 $&;什么意思

1 : #!/usr/local/bin/perl
2 :
3 : while ($inputline = ) {
4 : while ($inputline =~ /\b[A-Z]\S+/g) {
5 : $word = $&;
6 : $word =~ s/[;.,:-]$//; # remove punctuation
7 : $wordlist{$word} += 1;
8 : }
9 : }
10: print ("Capitalized words and number of occurrences:\n");
11: foreach $capword (keys(%wordlist)) {
12: print ("$capword: $wordlist{$capword}\n");
13: }

新手求解释,而且我这段代码运行不起来的,那里错了?
最主要的是第5行, $word = $&;
中的 $& 是什么意思!

Answer 1

#!/usr/local/bin/perl

while ($inputline =(<>) ) { #这段。
while ($inputline =~ /\b[A-Z]\S+/g) {
$word = $&;
$word =~ s/[;.,:-]$//; # remove punctuation
$wordlist{$word} += 1;
}
}
print ("Capitalized words and number of occurrences:\n");
foreach $capword (keys(%wordlist)) {
print ("$capword: $wordlist{$capword}\n");
}

Perl一些内置常量:
是这样
$& :与格式匹配的字符串
$` : 格式匹配信息前的字符串
$’: 格式匹配信息后的字符串

例如：
$inputline =" 12 asdf Capliz qqr 124";
$inputline =~ /\b[A-Z]\S+/;

$`:"12 asdf "
$&:"Capliz"
$':" qqr 124"

Answer 2

如果一个模式成功匹配上，$`, $&, $’将被设置，分别表示匹配左边、匹配、匹配右边的字符串,

while ($inputline = ) 这个应该是多行读取吧?