我亲眼看到了这个一角。
perl -lane $_{$F[0]}+=$F[1]}print"$_ $_{$_}"for keys%_;{ file
如何根据另一列中的值对列中的值进行求和?这里。
and I don t remember how the "{" at the end works. Could someone explain how it works?
我亲眼看到了这个一角。
perl -lane $_{$F[0]}+=$F[1]}print"$_ $_{$_}"for keys%_;{ file
如何根据另一列中的值对列中的值进行求和?这里。
and I don t remember how the "{" at the end works. Could someone explain how it works?
来自Perl 帮助:
-n assume "while (<>) { ... }" loop around program
这只是一个纯文本操作,所以它会得到这个程序:
while (<>) { $_{$F[0]}+=$F[1]}print"$_ $_{$_}"for keys%_;{ }
这是对-n
开关的滥用,因为由于原始程序中没有匹配的}
,while循环被提前关闭。但是由-n
开关添加的闭合}
仍然需要匹配一个东西,这就是为什么即使它不执行任何操作,程序末尾仍需要额外的{
。
换句话说,最后一个{
的唯一原因是为了避免语法错误。
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