如何去掉重复的行

sunzhiguolu

回复 20# rubyish
谢谢您的指导

1. #!/usr/bin/perl
   
2. use strict;
   
3. use warnings;
   
4. 
   
5. my @aData = ();
   
6. while(<DATA>){
   
7.     my ($t) = /\A(\S{2})/;
   
8.     my ($pos) = grep {$t eq $aData[$_][0]} 0 .. $#aData;
   
9.     defined($pos) ? push(@{$aData[$pos][-1]}, $_) : push(@aData, [$t,[$_]]);
   
10. }
    
11. 
    
12. foreach (grep {@{$_->[-1]} == 1} @aData){
    
13.     print($_->[-1][0]);
    
14. }
    
15. 
    
16. __DATA__
    
17. sdfsdfxxx
    
18. sdfsdcccc
    
19. sfv
    
20. vb
    
21. delA
    
22. cb
    
23. delB
    
24. cbb
    
25. delC
    
26. zxc
    
27. cvbn
    
28. againA
    
29. cbEND
    
30. break
    
31. againB
    

复制代码

my @aData = ();
my ($pos) = grep {$t eq $aData[$_][0]} 0 .. $#aData;

VS

my @aData = [];
my ($pos) = grep {$t eq $aData[$_][0]} 0 .. $#aData;

Running ... err
Use of uninitialized value in string eq ...

两种赋值方式，引用时有何区别？

rubyish

回复 21# sunzhiguolu

有何区别？

1. my $t = 'x';
   
2. my @A = ();
   
3. my ($pos1) = grep { $t eq $A[$_][0] } 0 .. $#A;
   
4. 
   
5. # 0 .. $#A EQ  0 .. -1 => SKIP

复制代码

1. my @B = [];
   
2. my ($pos2) = grep { $t eq $B[$_][0] } 0 .. $#B;
   
3. 
   
4. # $B[0]     => []
   
5. # $B[0][0]  => uninitialized value

复制代码

1. my @B = ['x'];
   
2. my ($pos2) = grep { $t eq $B[$_][0] } 0 .. $#B;
   
3. 
   
4. # $B[0]     => ['x']
   
5. # $B[0][0]  => 'x'
   
6. say $pos2;    # 0
   
7. 
   
8. my @B = ['z'];
   
9. my ($pos2) = grep { $t eq $B[$_][0] } 0 .. $#B;
   
10. say $pos2;    # Use of uninitialized value $pos2

复制代码

my @A = ();
EQ my @A;
say $#A;      # -1, length == 0

my @B = [];
EQ my @B = ( [] );    # 1 elem, a empty arrayref
say $#B;              # 0, length == 1

@B = ( () );                    # empty
@B = ( ( () ) );                # empty
@B = ( ( ( ( ( () ) ) ) ) );    # empty
say( ( ( ( ( ( ( ("HELP!!") ) ) ) ) ) ) );
EQ say "HELP!!";

my @b = 1;
EQ my @b = (1);

my @a = 1, 2, 3;
EQ my @a = 1;                   # discard 2, 3

my $a = 1, 2, 3;
EQ my $a = 1;                   # discard 2, 3

my $a = ( 11, 22, 33 );
EQ my $a = 33;                  # last

my $C = ( print("A"), print("B"), 'C' );

leisi:

print('A');  # eval print('A'), discard return value
print('B');
my $C = 'C';

leisi:

my $C = do {
    print 'A';
    print 'B';
    'C';
};

rubyish

d   e  l  ~  ~