В Perl, как я могу соединить первые две строки ввода?

Question

Как преобразовать с помощью Perl эту мультилинию:

Colours:
Red
Green
Yellow
Blue

В:

Colours: Red
Green
Yellow
Blue

Answer 1

Графема Unicode: \R и поддерживается начиная с версии 5.10.

Таким образом, вы можете изменить первый разрыв строки на пробел во всем файле следующим образом:

$ perl -Mv5.10 -CSD -i.orig -0777 -pe 's/\R/ /' some_utf8_file.txt

Есть и другие способы, которые не так бесполезны в памяти, но они могут быть сложными, чтобы получить право. Вы можете опустить -0777 и посмотреть, достаточно ли это хорошо для вас в этом случае.

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РЕДАКТИРОВАТЬ: Regex Escape

Вот экранирование, поддерживаемое в регулярных выражениях, включая версию, в которой он был впервые поддержан, с номерами выпусков, округленными до четного, начиная с v5.6.

Release  Rx Escape   Meaning
=======  ==========  ===========================================================================================
v1.0     \0          Match character number zero (U+0000, NULL, NUL).
v1.0     \0N,\0NN    Match octal character up to octal 077.
v1.0     \N          Match Nth capture group (decimal) if not in charclass and that many seen, else (octal) character up to octal 377.
v1.0     \NN         Match Nth capture group (decimal) if not in charclass and that many seen, else (octal) character up to octal 377.
v1.0     \NNN        Match Nth capture group (decimal) if not in charclass and that many seen, else (octal) character up to octal 377.
v4.0     \a          Match the alert character (ALERT, BEL).
v5.0     \A          True at the beginning of a string only, not in charclass.
v1.0     \b          Match the backspace char (BACKSPACE, BS) in charclass only.
v1.0     \b          True at Unicode word boundary, outside of charclass only.
v1.0     \B          True when not at Unicode word boundary, not in charclass.
v4.0     \cX         Match ASCII control character Control-X (\cZ, \c[, \c?, etc).
v5.6     \C          Match one byte (C char) even in UTF‑8 (dangerous!), not in charclass.
v1.0     \d          Match any Unicode digit character.
v1.0     \D          Match any Unicode nondigit character.
v4.0     \e          Match the escape character (ESCAPE, ESC, not backslash).
v4.0     \E          End case (\F, \L, \U) or quotemeta (\Q) translation, only if interpolated.
v1.0     \f          Match the form feed character (FORM FEED, FF).
v5.16    \F          Foldcase (not lowercase) till \E, only if interpolated.
v5.10    \g{GROUP}   Match the named or numbered capture group, not in charclass.
v5.0     \G          True at end-of-match position of prior m//g or pos() setting, not in charclass.
v5.10    \h          Match any Unicode horizontal whitespace character.
v5.10    \H          Match any Unicode character except horizontal whitespace.
v5.10    \k<GROUP>   Match the named capture group; also \k'NAME', not in charclass.
v5.10    \K          Keep text to the left of \K out of match, not in charclass.
v4.0     \l          Lowercase (not foldcase) next character only, only if interpolated.
v4.0     \L          Lowercase (not foldcase) till \E., only if interpolated.
v1.0     \n          Match the newline character (usually LINE FEED, LF).
v5.12    \N          Match any character except newline.
v5.6     \N{NAME}    Match the named character or named alias, or if outside of charclass named sequence, but only if interpolated and charnames loaded.
v5.14    \o{NNNNNN}  Match the character given in any number of octal digits.
v5.6     \p{PROP}    Match any character with the named property.
v5.6     \P{PROP}    Match any character without the named property.
v4.0     \Q          Quote (de-meta) metacharacters till \E.
v1.0     \r          Match the return character (usually CARRIAGE RETURN, CR).
v5.10    \R          Match any Unicode linebreak grapheme, only outside of charclass.
v1.0     \s          Match any Unicode whitespace character except \cK.
v1.0     \S          Match any Unicode nonwhitespace character or \cK.
v1.0     \t          Match the tab character (CHARACTER TABULATION, HT).
v4.0     \u          Titlecase (not uppercase) next character only, only if interpolated.
v4.0     \U          Uppercase (not titlecase) till \E, only if interpolated.
v5.10    \v          Match any Unicode vertical whitespace character.
v5.10    \V          Match any character except Unicode vertical whitespace.
v1.0     \w          Match any Unicode “word” character (alphabetics, digits, combining marks, and connector punctuation)
v1.0     \W          Match any Unicode nonword character.
v4.0     \xH         Match the character given in one hex digit.
v4.0     \xHH        Match the character given in two hex digits.
v5.6     \x{HHHHHH}  Match the character given in any number of hex.
v5.6     \X          Match Unicode extended grapheme cluster, only outside of charclass.
v5.5     \z          True at end of string only.
v5.0     \Z          True right before optional final newline.

Answer 2

Интересный случай, когда вы читаете из файла построчно:

#!/usr/bin/perl

use strict; use warnings;

if (defined(my $first = <DATA>)) {
    chomp $first;
    if (defined(my $second = <DATA>)) {
        $first .= $second
    }
    print $first;
}

print while <DATA>;

__DATA__
Colours:
Red
Green
Yellow
Blue

Answer 3

Простой вопрос, легкий ответ:

#!/usr/bin/perl

use strict;
use warnings;

my $str = 'Colours:
Red
Green
Yellow
Blue';

$str =~ s/\n/ /;

print "$str\n";

Answer 4

как насчет:

$string =~ s/\n/ /;