還是跑來求幫助了...

babyma1109

第一題吧:
Write a Perl program P1.pl to greet whatever is passed to it on the command line,
e.g.,
Hello, stranger!
There can be a problem with the above script: a parameter must be supplied, otherwise we'll get an error message.

comp315@turing> ./P1.pl
Use of uninitialized value $thing in concatenation (.)
or string at ./P1.pl line 4.
Hello, !
You should write the script in such a way that it will print a default value, let's say
\world", if no value is supplied on the command line.
comp315@turing> ./P1.pl
Hello, world!
Pay attention when providing zero as a parameter, as the greeting should be
comp315@turing> ./P1.pl 0
Hello, 0!
Modify the script to say \Goodbye" according to whether the -b switch was used on
the command line and the corresponding comment will be the output:
>P1.pl                             # Hello, world!
>P1.pl student                # Hello, student!
>P1.pl -b                        # Goodbye, world!
>P1.pl -b 'nice student'   # Goodbye, nice student!


第二題吧, 改錯(cuò)這個(gè)我沒怎么看懂有誰能幫我看看咩
The following program is supposed to read text from standard input and to output
them sorted by length. The lines are read in an array called @lines. Based on
@lines, a new array @sortarray is created such that each element of this array is the
length of a line of text, concatenated with the vertical bar `|' character, concatenated
with the index of that line of text in the original array @lines. The program sorts
the new array, and then uses the results to display the original lines in sorted order.

#!/usr/bin/perl
use strict;
use warnings;

my @lines;
my @sortarray;
# read in the entire input
@lines = <STDIN>;

#construct the array with the length prepended
foreach (0 .. $#lines) {
  $sortarray[$_] = length($lines[$_]) . "|" . $_;
}

# sort using numeric comparison
@sortarray = sort { $a <=> $b } @sortarray;

# display results
print "****************************************\n";
foreach (@sortarray) {
  print $lines[substr($_, index($_, "|"))];
}

afukada

請問第一題可不可以使用module

babyma1109

#!/usr/bin/perl
use strict;
use warnings;

my $person ='world';
if( @ARGV)
{
$person = $ARGV[0];
}
print "Hello ".$person," ! \n";
這是我寫的東西...
好像沒有用到回復(fù) 2# afukada


   

rubyish

第一題:

1. #!/usr/bin/perl
   
2. use 5.016;
   
3. @ARGV = map { $_ // 'world' } @ARGV[ 0, 1 ];
   
4. my @greet = ( "Hello, $ARGV[0]!", "Goodbye, $ARGV[1]!" );
   
5. say $greet[ $ARGV[0] eq '-b' ];
   

復(fù)制代碼

rubyish

第二題:
改錯(cuò)

1. my @sortarray;
   
2. my @lines = <>;
   
3. for ( 0 .. $#lines ) {
   
4.     my $l = length $lines[$_];
   
5.     $sortarray[$_] = [ $l, $l . "|" . $_ ];
   
6. }
   
7. @sortarray = map { $_->[1] } sort { $a->[0] <=> $b->[0] } @sortarray;
   
8. 
   
9. print "****************************************\n";
   
10. for (@sortarray) {
    
11.     print $lines[ substr( $_, index( $_, "|" ) + 1 ) ];
    
12. }

復(fù)制代碼

改寫:

1. 
   
2. my @lines = <>;
   
3. print "****************************************\n";
   
4. print map { $_->[1] } sort { $a->[0] <=> $b->[0] } map [ length, $_ ], @lines;
   

復(fù)制代碼

babyma1109

話說 改錯(cuò)這個(gè) 沒怎么看懂.....回復(fù) 12# rubyish


   

rubyish

回復(fù) 13# babyma1109


    一個(gè)簡潔優(yōu)雅的代碼 ...非常簡短。

1. 
   
2. my @a = map { $_ // 'world' } @ARGV[ 0, 1 ];
   
3. say $a[0] ne '-b' ? "Hello, $a[0]!" :  "Goodbye, $a[1]!"
   

復(fù)制代碼

唐歸來

回復(fù) 16# rubyish


   請教一下  $_ // 'world' 是什么意思啊

rubyish

回復(fù) 17# 唐歸來

1. $_ // 'world' 是什么意思啊

復(fù)制代碼

1. defined $_ ? $_ : 'world'

復(fù)制代碼

babyma1109

不愧是大神級別的  比我這種屌絲寫的好多了回復(fù) 20# ypqfyf


   

Perlvim

回答了題是不是可以推薦工作？

rubyish

NaN!!{:3_188:}{:3_188:}

babyma1109

第一題 我只寫出了第一部分....
怎么加-b讓他交換就不太明白了
回復(fù) 2# afukada


   

babyma1109

哈哈  想太多了  回答了就能寫作業(yè)了
回復(fù) 3# Perlvim


   

babyma1109

這個(gè)  話說我也是  可是米有辦法
回復(fù) 4# sinian126


   

babyma1109

老師還說...你要想拿extra point, 就要把甚么格式寫的好看點(diǎn)啊
如果人家輸入的是-c 你要告訴別人只能是-b才行甚么的  
很是頭大啊回復(fù) 5# rubyish