% perl -le 'print"@{[split//,join q(x),split/(?<=c)/,join(q(),qw(a b c d c e foo f)),2]}"'
a b c x d c e f o o f
####
% perl -le 'print"@{[split//,join q(x),split/(?<=c)/,join(q(),qw(a b c d c e),q( ),q(f)),2]}"'
a b c x d c e f
####
perl -le 'print"@{[split/\0/,join qq(\0x),split/(?<=c)/,join(qq(0),qw(a b c d c e foo f)),2]}"'
a b c x d c e foo f