Getting started with Perl-Chapter 9-using regular expressions to process text-Exercises

1. Question

2. Code and Output

1 #-----------------------------------------------------------#
2 # Source: Learning Perl, chapter9, exercise-1
3 # Date: 2012-01-19
4 # Author: xiaodongrush
5 #-----------------------------------------------------------#
6 Use 5.010;
7 @ array = QW {
8. fredfred
9 fredfredbarney
10 barneyfredfred
11 barneybarneybarney
12 Fred | barney
13 };
14 @ content = QW {
15 Fred | barney
16 };
17 foreach $ what (@ content ){
18 say "\ $ what = $ what ";
19 say "\ @ array = (@ array )";
20 foreach $ text (@ array ){
21 if ($ text = ~ M /(? : $ What) {3 }/){
22 say "<$ '> <$ &> <$'> ";
23}
24}
25 say "----------------------------";
26}
27 <STDIN>;
28 #-----------------------------------------------------------#
29 # repeat a string three times. Note that this string may contain or | such a character, so it is enclosed in parentheses.
30 # It should be included.
31 #-----------------------------------------------------------#

1 #-----------------------------------------------------------#
2 # Source: Learning Perl, chapter9, exercise-2
3 # Date: 2012-01-19
4 # Author: xiaodongrush
5 #-----------------------------------------------------------#
6 Use 5.010;
7 $ input_file = $ argv [0];
8 $ output_file = $ argv [0]. ". Out ";
9 Unless (! Open in, "<$ input_file "){
10 say "can't read <$ input_file>! ";
11}
12 unless (open out, "> $ output_file "){
13 say "can't write <$ output_file>! ";
14}
15 while (<in> ){
16 S/Fred/Larry/GI;
17 print out $ _;
18}
19 #-----------------------------------------------------------#
20 # Read-Only <, write only>, append write>. The default value is read/write.
21 #-----------------------------------------------------------#

1 #-----------------------------------------------------------#
2 # Source: Learning Perl, chapter9, exercise-3
3 # Date: 2012-01-19
4 # Author: xiaodongrush
5 #-----------------------------------------------------------#
6 Use 5.010;
7 $ text = "Fred & Wilma & Fred & WIMA ";
8 say "text = $ text ";
9 @ array = Split/Fred/GI, $ text;
10 foreach (@ array ){
11 S/Wilma/Fred/GI;
12}
13 $ text = join Wilma, @ array;
14 say "text = $ text ";
15 <stdin>;
16 #-----------------------------------------------------------#
17 #1. This solution uses Fred as the delimiter to separate strings.
18 # Wilma sanitation Fred in the string, and then use wilma to connect the separate string
19 #2. The solution in the book is to replace Fred
20 # \ n. Then, replace wilma with Fred and \ n with Wilma.
21 #-----------------------------------------------------------#

 

1 #-----------------------------------------------------------#
2 # Source: Learning Perl, chapter9, exercise-4
3 # Date: 2012-01-19
4 # Author: xiaodongrush
5 #-----------------------------------------------------------#
6 use 5.010;
7 $ ^ I = ". bak ";
8 $ text = "# Copyright (C) 2012 by Yours Truly \ n ";
9 while (<> ){
10 if (/#! /){
11 $ _ = $ _. $ text;
12}
13 print $ _;
14}
15 #-----------------------------------------------------------#
16 #1./I indicates case-insensitive,/G indicates global match
17 #2. Change the file name to word.txt. out first,
18 # After creating an empty word.txt file, connect each line of word.txt. Out,
19 # And write it to the word.txt file through printlinks.
20 #-----------------------------------------------------------#

1 #-----------------------------------------------------------#
2 # Source: Learning Perl, chapter9, exercise-4
3 # Date: 2012-01-19
4 # Author: xiaodongrush
5 #-----------------------------------------------------------#
6 Use 5.010;
7 $ text = "# copyright (c) 2012 by yours truly \ n ";
8 foreach (@ argv ){
9 $ files {$ _} = 1;
10}
11 while (<> ){
12 if (/# copyright /){
13 delete $ files {$ argv };
14}
15}
16 @ argv = keys % files;
17 $ ^ I = ". Bak ";
18 if (@ argv! = 0 ){
19 while (<> ){
20 if (/#! /){
21 $ _ = $ _. $ text;
22}
23 Print $ _;
24}
25}
26 #-----------------------------------------------------------#
27 #1./I indicates case-insensitive,/G indicates global match
28 #2. Change the file name to word.txt. out first,
29 # After creating an empty word.txt file, connect each line of word.txt. Out,
30 # And write it into the word.txt file through printlinks.
31 #-----------------------------------------------------------#

Output omitted, similar to the previous question.

3. File

/Files/pangxiaodong/learns ningperl/ch9-answer.rar