Perl语言入门-第九章-用正则表达式处理文本-习题

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1. 题目

2. 代码与输出

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   fredfredfred
9   fredfredbarney
10   barneyfredfred
11   barneybarneybarney
12   fred|barney
13 };
14 @content = qw {
15   fred 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 # 将某个字符串重复3次，注意这个字符串可能包含或|这样的字符，因此将其用括号
30 # 括起来就好了
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 # 只读<，只写>，追加写>>，默认就是读写
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&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.该解法是用Fred作为分割符，将字符串分开，然后，将分开的
18 #  字符串中的wilma环卫Fred，然后再用Wilma将分开的字符串连起来
19 #2.书中解法是，首先对字符串chomp，保证不含\n，然后将Fred都换为
20 #  \n，接着讲Wilma都换为Fred，最后将\n都换为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表示忽略大小写，/g表示全局匹配
17 # 2. $^I，在读入文件假设是word.txt，首先将其改名为word.txt.out，
18 #    然后创建一个空的word.txt文件，接着，word.txt.out的每一行，
19 #    并且通过print函数写入到word.txt文件中。
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表示忽略大小写，/g表示全局匹配
28 # 2. $^I，在读入文件假设是word.txt，首先将其改名为word.txt.out，
29 #    然后创建一个空的word.txt文件，接着，word.txt.out的每一行，
30 #    并且通过print函数写入到word.txt文件中。
31 #-----------------------------------------------------------#

输出略，与前一题类似。

3. 文件

/Files/pangxiaodong/LearningPerl/ch9-answer.rar