我想跳到包含"include"的第一行.
<> until /include/;
为什么这不起作用?
匹配运算符默认使用,$_
但默认情况下<>
运算符不会存储$_
,除非它在while循环中使用,因此不会存储任何内容$_
.
来自perldoc perlop
:
I/O Operators ... Ordinarily you must assign the returned value to a variable, but there is one situation where an automatic assignment happens. If and only if the input symbol is the only thing inside the conditional of a "while" statement (even if disguised as a "for(;;)" loop), the value is auto? matically assigned to the global variable $_, destroying whatever was there previously. (This may seem like an odd thing to you, but you’ll use the construct in almost every Perl script you write.) The $_ vari? able is not implicitly localized. You’ll have to put a "local $_;" before the loop if you want that to happen. The following lines are equivalent: while (defined($_ = )) { print; } while ($_ = ) { print; } while () { print; } for (;;) { print; } print while defined($_ = ); print while ($_ = ); print while ; This also behaves similarly, but avoids $_ : while (my $line = ) { print $line }