1. 題目
2. 代碼與輸出
1 #-----------------------------------------------------------#
2 # Source: Learning Perl, chapter10,exercise-1
3 # Date: 2012-01-20
4 # Author: xiaodongrush
5 #-----------------------------------------------------------#
6 use 5.010;
7 $secret_num = int(1 + rand 100);
8 while(<STDIN>) {
9 chomp;
10 if(/^[0-9]+$/) { # 鍵入都是數字
11 if($_ < $secret_num) {
12 say "Too low. Try again.";
13 } elsif($_ > $secret_num) {
14 say "Too high. Try again.";
15 } else {
16 say "You get it.";
17 last;
18 }
19 } elsif(/^quit$|^exit$|^\s*$/) { # quit,exit,空白行
20 last;
21 } else {
22 say "Not Vaild Input. Try again";
23 }
24 }
25 #-----------------------------------------------------------#
1 #-----------------------------------------------------------#
2 # Source: Learning Perl, chapter10,exercise-2
3 # Date: 2012-01-20
4 # Author: xiaodongrush
5 #-----------------------------------------------------------#
6 use 5.010;
7 $secret_num = int(1 + rand 100);
8 if(@ARGV[0] =~ /-debug/i) {
9 say "[DEBUG] The secret num is $secret_num";
10 }
11 while(<STDIN>) {
12 chomp;
13 if(/^[0-9]+$/) { # 鍵入都是數字
14 if($_ < $secret_num) {
15 say "Too low. Try again.";
16 } elsif($_ > $secret_num) {
17 say "Too high. Try again.";
18 } else {
19 say "You get it.";
20 last;
21 }
22 } elsif(/^quit$|^exit$|^\s*$/) { # quit,exit,空白行
23 last;
24 } else {
25 say "Not Vaild Input. Try again";
26 }
27 }
28 #-----------------------------------------------------------#
1 #-----------------------------------------------------------#
2 # Source: Learning Perl, chapter10,exercise-3
3 # Date: 2012-01-20
4 # Author: xiaodongrush
5 #-----------------------------------------------------------#
6 use 5.010;
7 $ENV{"ZERO"} = 0;
8 $ENV{"EMPTY"} = '';
9 $ENV{"UNDEFINED"} = undef;
10 $max_key_len = 0;
11 $key_len_limit = 10;
12 $value_len_limit = 10;
13 while(($key,$value) = each %ENV) {
14 if(length($key) > $key_len_limit) {
15 next;
16 }
17 $max_key_len = $max_key_len > length($key) ? $max_key_len : length($key);
18 }
19 say "1234567890" x 7;
20 while(($key,$value) = each %ENV) {
21 if(length($key) > $key_len_limit || length($value) > $value_len_limit) {
22 next;
23 }
24 printf "%" . $max_key_len . "s " . "%s\n", $key, $value // "(undefined)";
25 }
26 #-----------------------------------------------------------#
27 # 如果$value='',那麼$value || "(undefined)" 返回"(undefined)"
28 # 如果$value='',那麼$value // "(undefined)" 返回'';
29 # 如果$value=undef,$value || "(undefined)"
30 # 和$value // "(undefined)"都返回"(undefined)"
31 #-----------------------------------------------------------#
3. 檔案
/Files/pangxiaodong/LearningPerl/ch10-answer.rar