...(meta character)是一种Perl风格的正则表达式,只有一部分文本处理工具支持它,并不是所有的文本处理工具都支持。 1.4K10 Perl语言入门系列之一 ①单引号内的字符串直接量 单引号内的字符串直接量指的是'…'内的一串字符,除单引号本身和反斜线外,单引号内的所有字符都代表他们本身,要表示单引号或者反斜线,在...
countdown赋值为10 因此,以下代码将不能正常工作: sub count_down { You can't use 'macro parameter character #' in math modecountdown还未定义 }; my _, 0 } @castaways; # 编译错误 Extra open brace or missing close bracecastaway}++; print "castaway:tab{ 转储闭包:使用Data::Dump::Streamer...
replacement string as the 4th argument. This allows you to replace parts of the EXPR and return what was there before in one operation, just as you can with "splice". mys="Theblackcatclimbedthegreentree";mys="Theblackcatclimbedthegreentree";myz = substrs, 14, 7, "jumped from"; # climb...
At a given character position, the first alternative that allows the regex match to succeed will be the one that matches. Here, all the alternatives match at the first string position, so the first matches. 分组与分层匹配 Grouping things and hierarchical matching ...
-00 empty string, but “\n+” paragraph mode -0014 8-bit character, in octal form feed -0xC 8-bit character, in hex form feed -0400 undef, above 8-bit slurp -0777 undef, idiomatic slurp -g undef slurp, new in v5.36 -0x1FF \777 character, include -C actual \777 -0x2603 wide...
Table 3.1. Escape sequences in strings. Escape Sequence Description \a Bell (beep) \b Backspace \cn The Ctrl+n character \e Escape \E Ends the effect of \L, \U or \Q \f Form feed \l Forces the next letter into lowercase
–`s/pattern/replacement/` – Search and replace a pattern in a string. –`tr/characters1/characters2/` – Transliterate characters in a string. –`grep /pattern/, @array` – Select array elements that match a pattern. –`split /pattern/, $string` – Split a string into an array base...
oct- convert a string to an octal number open- open a file, pipe, or descriptor opendir- open a directory ord- find a character's numeric representation our- declare and assign a package variable (lexical scoping) pack- convert a list into a binary representation ...
string boundary o Evaluates the expression only once s Allows use of . to match a newline character x Allows you to use white space in the expression for clarity g Replaces all occurrences of the found expression with the replacement text ...
$string="Hello world";$char=substr($string,0,1);# get the first characterprint$char;# prints H$char=substr($string,-1);# get the last characterprint$char;# prints dsubstr($string,0,1)="J";# replace the first character with Jprint$string;# prints Jello worldsubstr($string,-5)="B...