You need to compute the number of lines in a file.
Many systems have a wc program to count lines in a file:
$count = `wc -l < $file`; die "wc failed: $?" if $?; chomp($count);
You could also open the file and read line-by-line until the end, counting lines as you go:
open(FILE, "< $file") or die "can't open $file: $!"; $count++ while <FILE>; # $count now holds the number of lines read
Here's the fastest solution, assuming your line terminator really is "\n"
:
$count += tr/\n/\n/ while sysread(FILE, $_, 2 ** 16);
Although you can use -s
$file
to determine the file size in bytes, you generally cannot use it to derive a line count. See the Introduction to Chapter 9, Directories, for more on -s
.
If you can't or don't want to call another program to do your dirty work, you can emulate wc by opening up and reading the file yourself:
open(FILE, "< $file") or die "can't open $file: $!"; $count++ while <FILE>; # $count now holds the number of lines read
Another way of writing this is:
open(FILE, "< $file") or die "can't open $file: $!"; for ($count=0; <FILE>; $count++) { }
If you're not reading from any other files, you don't need the $count
variable in this case. The special variable $.
holds the number of lines read since a filehandle was last explicitly close
d:
1 while <FILE>; $count = $.;
This reads all the records in the file and discards them.
To count paragraphs, set the global input record separator variable $/
to the empty string (""
) before reading to make <> read a paragraph at a time.
$/ = ''; # enable paragraph mode for all reads open(FILE, $file) or die "can't open $file: $!"; 1 while <FILE>; $para_count = $.;
Your system's wc (1) manpage; the $/
entry in perlvar (1), and in the "Special Variables" section of Chapter 2 of Programming Perl; the Introduction to Chapter 9
Copyright © 2001 O'Reilly & Associates. All rights reserved.