You never assign anything to $_. Therefore, it is uninitialized.

"while" isn't suited for looping over an array. When looping over a filehandle, as:

    while (<$fh>)

the while implicitly assigns each line to $_ in turn. However, in the following:

    while (@foo)

the contents of the while expression are taken to be a boolean expression, which is true as long as there are elements in @foo, and doesn't assign anything to $_.

You may want to use the foreach keyword:

    foreach (@foo)

This will assign each element of @foo, in turn, to $_.

In reply to Re: stuck at "Use of uninitialized value in length at ..." by Sue D. Nymme
in thread stuck at "Use of uninitialized value in length at ..." by dr_joe

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