如何匹配两个空行之间的行？（结帖）

churchmice

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21^# churchmice 发表于 2008-03-20 12:52

最后说一下/c的作用,/c就是continue的意思
本来如果在m//g的时候匹配不成功则pos会被reset成undef
但是如果是m//gc的时候,如果匹配不成功则pos是不会发生变化的

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CODE:

#!/usr/bin/perl
use strict;
use warnings;
print "Test without /c modifier \n";
$_ = "this is a test";
/^this/g;
print "now the pos is ",pos,"\n";
/canotmatch/g;
print "now the pos is ",pos,"\n";

print "Test with /c modifier \n";
$_ = "this is a test";
/^this/g;
print "now the pos is ",pos,"\n";
/canotmatch/gc;
print "now the pos is ",pos,"\n";

QUOTE:

<lig@other-server:~/chinaunix>$ ./continue
Test without /c modifier
now the pos is 4
Use of uninitialized value in print at ./continue line 9.
now the pos is
Test with /c modifier
now the pos is 4
now the pos is 4

最后,可以用mastering regex里面的一张表来总结一下
Type of match Where match starts             pos upon success pos upon failure
m/⋯/             start of string (pos ignored) reset to undef             reset to undef
m/⋯/g             starts at target's pos             set to end of match reset to undef
m/⋯/gc             starts at target's pos             set to end of match left unchanged

__lxmxn__

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22^# __lxmxn__ 发表于 2008-03-21 02:00

QUOTE:

原帖由 churchmice 于 2008-3-20 12:52 发表
最后说一下/c的作用,/c就是continue的意思
本来如果在m//g的时候匹配不成功则pos会被reset成undef
但是如果是m//gc的时候,如果匹配不成功则pos是不会发生变化的

#!/usr/bin/perl
use strict;
use warnin ...

多谢兄弟耐心的讲解，明白很多了，感谢。