Without 'g' modifier: 
1.>perl -e 'use re(debug); $_ = 'aaabbb'; /(( a | c? )*)/x'
2.>perl -e 'use re(debug); $_ = 'aaabbb'; /(( a )* | ( c? )?)/x'

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In reply to Re^2: ZERO_LENGTH match by sh1tn
in thread ZERO_LENGTH match by sh1tn

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