[英]perl: reading from a file and/or stdin without using while(<>)
For cases where one wishes to avoid the useful while(<>)
syntax and manage file input manually, how does one handle the operation of reading from a list of files and/or STDIN
? 对于希望避免使用
while(<>)
语法并手动管理文件输入的情况,如何处理从文件列表和/或STDIN
中读取的操作? To read from files, one can simply iterate through @ARGV
, opening each element in turn (eg, my $file=shift @ARGV; open(my $fh,'<',$file); while(<$fh>) {...}; close($fh);
. To read from standard input, one can simply use while(<STDIN>) { ...}
. However, assuming the programmer expects similar types of data to be provided through STDIN and file arguments, the body of code within each while
loop would have to be duplicated. I have tried unsuccessfully to assign STDIN to a filehandle (eg, my $fh = \\*STDIN
or my $fh = *STDIN{IO}
, each of which I have seen suggested elsewhere on this website). In essence, I would like to iterate through all files as well as STDIN
and treat the input from each identically, but without using the handy while(<>)
syntax. Could you please sketch a solution to this problem? Thank you. 要读取文件,可以简单地遍历
@ARGV
,依次打开每个元素(例如, my $file=shift @ARGV; open(my $fh,'<',$file); while(<$fh>) {...}; close($fh);
要从标准输入中读取内容,可以简单地使用while(<STDIN>) { ...}
。但是,假设程序员希望通过STDIN提供类似类型的数据。和文件参数,每个while
循环中的代码正文都必须重复。我尝试将STDIN分配给文件句柄(例如, my $fh = \\*STDIN
或my $fh = *STDIN{IO}
,但均失败)本质上,我想遍历所有文件以及STDIN
并相同地对待每个文件的输入,但不使用方便的while(<>)
语法。画出解决这个问题的方法?谢谢。
With two-arg open (like <>
uses), you could do 打开两个参数(如
<>
使用),您可以执行
@ARGS = '-' if !@ARGV;
for my $qfn (@ARGV) {
open($fh, $qfn);
while (<$fh>) {
...
}
}
Which three-arg open
, I might do 哪个三个参数
open
,我可能会做
@ARGV = \*STDIN if !@ARGV;
for my $qfn (@ARGV) {
my $fh;
if (ref($qfn)) {
$fh = $qfn;
} else {
open($fh, '<', $qfn);
}
while (<$fh>) {
...
}
}
Another way (if you can use CPAN modules) is to use IO::All . 另一种方法(如果可以使用CPAN模块)是使用IO :: All 。
Read a file into a scalar variable: 将文件读入标量变量:
my $content1 < io('file1');
Another way to do it with IO::ALL: 使用IO :: ALL的另一种方法:
my $content2 = io('file1')->slurp;
Or if you want it in an array, with each line as an element: 或者,如果您希望将其放在一个数组中,并以每行作为元素:
my @lines = io('file1')->slurp;
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