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Perl 5 version 22.0 documentation
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# eof

Perl functions A-Z | Perl functions by category | The 'perlfunc' manpage

- eof FILEHANDLE

- eof ()
- eof

  Returns 1 if the next read on FILEHANDLE will return end of file or if FILEHANDLE is not open. FILEHANDLE may be an expression whose value gives the real filehandle. (Note that this function actually reads a character and then `ungetc` s it, so isn't useful in an interactive context.) Do not read from a terminal file (or call `eof(FILEHANDLE)` on it) after end-of-file is reached. File types such as terminals may lose the end-of-file condition if you do.

  An `eof` without an argument uses the last file read. Using `eof()` with empty parentheses is different. It refers to the pseudo file formed from the files listed on the command line and accessed via the `<>` operator. Since `<>` isn't explicitly opened, as a normal filehandle is, an `eof()` before `<>` has been used will cause `@ARGV` to be examined to determine if input is available. Similarly, an `eof()` after `<>` has returned end-of-file will assume you are processing another `@ARGV` list, and if you haven't set `@ARGV` , will read input from `STDIN` ; see I/O Operators in perlop.

  In a `while (<>)` loop, `eof` or `eof(ARGV)` can be used to detect the end of each file, whereas `eof()` will detect the end of the very last file only. Examples:

          # reset line numbering on each input file    while (<>) {        next if /^\s*#/;  # skip comments        print "$.\t$_";    } continue {        close ARGV if eof;  # Not eof()!    }    # insert dashes just before last line of last file    while (<>) {        if (eof()) {  # check for end of last file            print "--------------\n";        }        print;        last if eof();     # needed if we're reading from a terminal    }

  Practical hint: you almost never need to use `eof` in Perl, because the input operators typically return `undef` when they run out of data or encounter an error.