[英]How can I read the lines of a file into an array in Perl?
I have a file named test.txt that is like this: 我有一个名为test.txt的文件,如下所示:
Test
测试
Foo富
Bar酒吧
But I want to put each line in a array and print the lines like this: 但是我想把每一行放在一个数组中并打印出这样的行:
line1 line2 line3
line1 line2 line3
But how can I do this? 但是我怎么能这样做呢?
#!/usr/bin/env perl
use strict;
use warnings;
my @array;
open(my $fh, "<", "test.txt")
or die "Failed to open file: $!\n";
while(<$fh>) {
chomp;
push @array, $_;
}
close $fh;
print join " ", @array;
Here is my single liner: 这是我的单线:
perl -e 'chomp(@a = <>); print join(" ", @a)' test.txt
Explanation: 说明:
@a
array @a
数组 chomp(..)
- remove EOL symbols for each line chomp(..)
- 删除每行的EOL符号 @a
using space as separator @a
The most basic example looks like this: 最基本的示例如下所示:
#!/usr/bin/env perl
use strict;
use warnings;
open(F, "<", "test.txt") or die("Cannot open test.txt: $!\n"); # (1)
my @lines = ();
while(<F>) { chomp; push(@lines, $_); } # (2)
close(F);
print "@lines"; # (3) stringify
(1) is the place where the file is opened. (1)是文件打开的地方。
(2) File handles work nicely within list enviroments (scalar/list environments are defined by the left value), so if you assign an array to a file handle, all the lines are slurped into the array. (2)文件句柄在列表环境中很好地工作(标量/列表环境由左值定义),因此如果将数组分配给文件句柄,则所有行都会插入到数组中。 The lines are delimited (ended) by the value of
$/
, the input record separator. 这些行由
$/
(输入记录分隔符)的值分隔(结束)。 If you use English;
如果你
use English;
, you can use $IRS
or $INPUT_RECORD_SEPARATOR
. ,您可以使用
$IRS
或$INPUT_RECORD_SEPARATOR
。 This value defaults to the newline character \\n
; 此值默认为换行符
\\n
;
While this seemed to be a nice idea, I've just forgot the fact that if you print all the lines, the ending \\n
will be printed too. 虽然这似乎是一个不错的主意,但我忘了这样一个事实:如果你打印所有的行,结尾
\\n
也将被打印出来。 Baaad me. 拜我
Originally the code was: 最初的代码是:
my @lines = <F>;
instead of the while
loop. 而不是
while
循环。 This is still a viable alternative, but you should swap (3) with chomp
ing and then printing/stringifying all the elements: 这仍然是一个可行的选择,但你应该交换(3)
chomp
然后打印/字符串化所有元素:
for (@lines) { chomp; }
print "@lines";
(3) Stringifying means converting an array to a string and inserting the value $"
between the array elements. This defaults to a space. (3)字符串化意味着将数组转换为字符串并在数组元素之间插入值
$"
。默认为空格。
See: the perlvar page . 请参阅: perlvar页面 。
So the actual 2nd try is: 所以实际的第二次尝试是:
#!/usr/bin/env perl
use strict;
use warnings;
open(F, "<", "test.txt") or die("Cannot open test.txt: $!\n"); # (1)
my @lines = <F>; # (2)
close(F);
chomp(@lines);
print "@lines"; # (3) stringify
One more answer for you to choose from: 还有一个答案供您选择:
#!/usr/bin/env perl
open(FILE, "<", "test.txt") or die("Can't open file");
@lines = <FILE>;
close(FILE);
chomp(@lines);
print join(" ", @lines);
If you find yourself slurping files frequently, you could use the File::Slurp module from CPAN: 如果您经常发现自己正在使用文件,可以使用CPAN中的File :: Slurp模块:
use strict;
use warnings;
use File::Slurp;
my @lines = read_file('test.txt');
chomp @lines;
print "@lines\n";
This is the simplest version I could come up with: 这是我能想到的最简单的版本:
perl -l040 -pe';' < test.txt
Which is roughly equivalent to: 这大致相当于:
perl -pe'
chomp; $\ = $/; # -l
$\ = 040; # -040
'
and: 和:
perl -e'
LINE:
while (<>) {
chomp; $\ = $/; # -l
$\ = " "; # -040
} continue {
print or die "-p destination: $!\n";
}
'
This is the code that do this (assume the below code inside script.pl) : 这是执行此操作的代码(假设下面的代码在script.pl中):
use strict;
use warnings
my @array = <> ;
chomp @array;
print "@array";
It is run by: 它由以下人员运行:
scirpt.pl [your file]
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