eof in perl- going in infinite loop -

when checking eof condition being false, it's going in infinite loop. here doing.

tie @lines, 'tie::file' , "abc.txt" or die;  (my $i=0; ; $i++) {     # if put if(!eof())condition instead of below one,      # goes in infinite loop.  may know why?     if ($lines[$i] =~ /^[\s]*hello/) {     splice @lines, $i, 1, "#$lines[$i]", "hi";     last;     }      #below eof condition working     if(eof){         last;     } } 

an eof without argument uses last file read. using eof() empty parentheses different. refers pseudo file formed files listed on command line , accessed via <> operator.

edit:

normally dont need use eof, because input operators typically return undef when run out of data, or if there error.

code:

maybe problem is, dont use 2nd condition of for loop.

tie @lines, 'tie::file' , "abc.txt" or die;  for(my $i=0;$i<=$#lines; $i++) {     if ($lines[$i] =~ /^[\s]*hello/){         splice @lines, $i, 1, "#$lines[$i]", "hi";         last;     } }