You may want to use the foreach keyword:

In general, that's a good solution. In this case, you'd end up with 

my @all_words = <FH1> ;
foreach (@all_words) {

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which is a needless waste of memory. The following is much more appropriate: 
while (<FH1>) {

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which is short for 
while (defined($_ = <FH1>)) {

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In reply to Re^2: stuck at "Use of uninitialized value in length at ..." by ikegami
in thread stuck at "Use of uninitialized value in length at ..." by dr_joe

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