Inserting a character to a line

pinpe has asked for the wisdom of the Perl Monks concerning the following question:

Hi, How do I insert character (e.g. , or .) at certain positions in a line? For example I want to insert a period ( . ) after the first 4 characters of every each line in the file. I cannot do it in sed command. I'm playing with my script using perl command but to no avail. Please advice. Thanks in advance. See below: Input:

12345
67890
23456
78901
34567
[download]

Desired Output:

1234.5
6789.0
2345.6
7890.1
3456.7
[download]

Br, Pete

Comment on Inserting a character to a line Select or Download Code

Replies are listed 'Best First'.
Re: Inserting a character to a line by pc88mxer (Vicar) on Mar 22, 2008 at 01:08 UTC
Two approaches come to mind: `substr($x, 4, 0, "."); # method 1 $x =~ s/\A(....)/$1./; # method 2` [download] The second approach can also be implemented with `sed`: `sed -e 's/^(....)/\1./'` [download] Anchoring the regular expression using `^` may not be necessary depending on your situation.	[reply] [d/l] [select]
Re^2: Inserting a character to a line by pinpe (Novice) on Mar 22, 2008 at 01:41 UTC
Hi pc88mxer, Cool!! method 2 works on me! Tnx bro! Br, Pete	[reply]
Re: Inserting a character to a line by ikegami (Patriarch) on Mar 22, 2008 at 01:27 UTC
A few ways: `substr($_, 4, 0, '.'); # at least 4 characters long substr($_, 4, 0) = '.'; # at least 4 characters long $_ =~ s/^(.{4})/$1./; $_ =~ s/(?<=^.{4})/./; pos($_)=4; $_ =~ s/\G/./; # at least 4 characters long $_ .= '.' . chop($_); # exactly 5 chars long $_ /= 10; # a 5 digit number without leading 0s $_ = sprintf('%06.1f', $_/10); # a 5 digit number` [download] The first one is probably fastest and the clearest.	[reply] [d/l]