Re: File Sorting Question

Well, a seeker would create a subroutine like this:

@temp = map { s/^The // } @indata;
@sorted = sort {lc($a) cmp lc($b) } @temp;
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I made a temp array so as not to keep the changes the substitution made.

Update: Actually, it *does not* alter the original values. Note that I assign the map s/// to @temp; @indata remains unchanged. This, from the manpage for map(type it in on this site's search box, for ease).

    %hash = map { getkey($_) => $_ } @array;

is just a funny way to write 


    %hash = ();
    foreach $_ (@array) {
        $hash{getkey($_)} = $_;
    }
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Update (number two): My mistake. . . I did test the code, though I changed it slightly and didn't think to test it again. I'm sorry--I misread the manpage, and misinterpreted what they were doing. This code should do what I meant in the first place:

@temp = map {my $tmp; ($tmp = $_) =~ s/^The //; $tmp} @indata
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Comment on Re: File Sorting Question Select or Download Code

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Re: Re: File Sorting Question by runrig (Abbot) on Jun 19, 2001 at 01:48 UTC
You'll find that your s/// has changed your original data. And your 'sorted' array no longer has the word 'The'. Update:And your map is a 'funny' way to write (thanks for pointing out another bug :-): `for (@array) { my $num = s/^The //; push @temp, $num; }` [download] which DOES modify the original @array. And doesn't put the desired value into @temp ($num is the number of substitutions, which is 0 (undef) or 1).	[reply] [d/l]
Re: Re: Re: File Sorting Question by tye (Sage) on Jun 19, 2001 at 10:46 UTC
`s/^The\s+// for @temp= @array;` - tye (but my friends call me "Tye")	[reply] [d/l]
Re: Re: File Sorting Question by chipmunk (Parson) on Jun 19, 2001 at 02:11 UTC
Yes, it does modify the original values, because the assignment to @temp occurs after the map, and after $_ has been changed in place for each element of @indata. Furthermore, substitution returns true or false; it does not return the modified string. Therefore, @temp will be a list of null strings and 1s, and @sorted will be a sorted list of null strings and 1s. Please test your code before posting it, or at least before contradicting a helpful correction from another Perl Monk. `#!/usr/local/bin/perl -w $, = "\n"; chomp(@indata = <DATA>); @temp = map { s/^The // } @indata; @sorted = sort {lc($a) cmp lc($b) } @temp; print @indata, "---", @temp, "---", @sorted, "---\n"; __DATA__ The Dog A Bird The Cat Lots of Fish` [download] And the output: `Dog A Bird Cat Lots of Fish --- 1 1 --- 1 1 ---` [download]	[reply] [d/l] [select]