Re: While.For loop noob query

For a small file (1 to 100 lines would qualify), you can just read the whole thing into an array at the start. Then you know how many lines you have.

  my @lines = <TXTIN>;
  for (@lines[0..($#lines - 1)]) {
    s/yada/yadda/;
  }
  $lines[-1] =~ s/different/substitution/;
[download]

Caution: Contents may have been coded under pressure.

Comment on Re: While.For loop noob query Download Code

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Re^2: While.For loop noob query by jriggs420 (Sexton) on Oct 06, 2005 at 15:05 UTC
Hi Roy, Quick follow up if you are still in here..What is this doing? `for (@lines[0..($#lines - 1)])` [download] it's kind of hard for me to see what's going on..Would you mind translating somewhat so I can adjust to my particular needs, if necessary. Thanks again	[reply] [d/l]
Re^3: While.For loop noob query by Roy Johnson (Monsignor) on Oct 06, 2005 at 15:17 UTC
It's going through all the elements of @lines except the last one. `$#lines` is the index of the last element of `@lines`. So `0..($#lines - 1)` is therefore the range from zero to index of the next-to-last element. So `@lines[0..($#lines - 1)]` is a slice of all but the last element. Caution: Contents may have been coded under pressure.	[reply] [d/l] [select]
Re^3: While.For loop noob query by ikegami (Patriarch) on Oct 06, 2005 at 15:20 UTC
`$#lines` is the index of the last elements of the array `@lines`. Let's say you have 10 lines. Their indexes would be 0 through 9, so `$#lines` would be 9. `@lines[ LIST ]` is an array slice. It returns a list formed from the elements indexed by LIST. In our earlier example, `@lines[0..($#lines - 1)]` returns elements 0 through 8. The `for` here starts a foreach loop over each element of the returned list. In other words, it loops over all up the last element of `@lines`. Since no variable name is specified, `$_` will hold the value for the current iteration. I think `$#array` and array slices are documented in perldata. Loops are documented in perlsyn.	[reply] [d/l] [select]