Between the kitten question and seeing this question at U&L about some sed magic, how about implementing tac?
Implement a program that will reverse and print the lines in a file.
A file, provided as a name or via standard input
The lines, reversed, to standard out.
Bytes of source code.
0i:1+?!v:a=?v}1+!
0.20r}~< >~}00
oa]~~.?)2l2dor[;!?l
It first counts the length of each line so it can isolate them in a separate stack when it browses back the lines to display them.
It can probably get shorter, I may work on it later.
inf str99 v using a.b
g a=-_n
so a
l v,noo noh
Expects input as a file called a.b, with each line no more than 99 characters. Reads in a file and labels the variable v. Makes a new variable called a with the negative index of it. Sort by the negative index (i.e. reverse order) and then list every thing in sorted (i.e. reverse) order.
For a longer length of lines, put quotes around each line and use (42 bytes):
insheet using a.b
g a=-_n
so a
l v,noo noh
-1 each reverse read0 hsym`$.z.x 0;
It isn't the best solution, but I guess it's something.
a=lambda x: f=open(x,'r');l=f.readlines();for o in reversed(l): print(o)
Any tips on golfing it further?
return outside of a def function is a syntax error. If you use a lambda, the return value is the result of the (single) expression.
\$\endgroup\$
l[::-1] instead of reversed(l) work? Also, you could remove the spaces after the :
\$\endgroup\$
(io.Source.stdin.getLines():\0){(a,b)=>println(a);0}
Bastardizing/side-effecting foldRight (:\) to deal with iterators (as returned by getLines) not having reverse
Not as short as I hoped.. But I tried!
using System.Linq;class c{static void Main(string[]a){foreach(var s in System.IO.File.ReadAllLines(a[0]).Reverse())System.Console.WriteLine(s);}}
using System.Linq;
class c
{
static void Main(string[]a)
{
foreach(var s in System.IO.File.ReadAllLines(a[0]).Reverse())
System.Console.WriteLine(s);
}
}
!Grev<cr>
Filters every line through the external command: rev. Must be run on linux.
cat -n|sort -nr|sed 's/^[^ ]* //'
j_.z
Takes input from STDIN
j_.z
.z # Input as list of lines
_ # reverse
j # join on newline
tacis a bit strange when it comes to trailing linefeeds. It transformsa\nb\n(trailing linefeed) intob\na\nanda\nb(no trailing linefeed) intoba\n. Is this how our code it supposed to behave? \$\endgroup\$tacis only a matter of time... \$\endgroup\$\n.tacreverses the order of these rows. If an\nis removed from the middle of the file, the row it terminated is joined to the next row, but in the case of the last line, there is no next row to join to. \$\endgroup\$