perl 正则前导字符

uat-prx02:/root# cat a1.pl 
my $str="123";
if ($str =~/(abc)*/){print "111111111
"};

uat-prx02:/root# perl a1.pl 
111111111

匹配 0 次或多次 abc 字符串


uat-prx02:/root# cat a1.pl 
my $str="abc";
if ($str =~/(abc)+/){print "111111111
"};
uat-prx02:/root# perl a1.pl 
111111111

uat-prx02:/root# cat a1.pl 
my $str="abcabc";
if ($str =~/(abc)+/){print "111111111
"};
uat-prx02:/root# perl a1.pl 
111111111

+: 一个或多个相同的前导字符(模式)


uat-prx02:/root# cat a1.pl 
my $str="abcabc";
if ($str =~/(abc){2}/){print "111111111
"};
uat-prx02:/root# perl a1.pl 
111111111

uat-prx02:/root# cat a1.pl 
my $str="abcc";
if ($str =~/(abc){2}/){print "111111111
"};
uat-prx02:/root# perl a1.pl 
uat-prx02:/root# ^C
uat-prx02:/root# ^C

匹配不上


uat-prx02:/root# cat a1.pl 
my $str="abcc";
if ($str =~/abc{2}/){print "111111111
"};
uat-prx02:/root# perl a1.pl 
111111111