Hello NisSam, and welcome to the Monastery!

Further to hippo’s answer, I just want to point out that even using exists doesn’t ensure that autovivification won’t occur:

 0:33 >perl -Mstrict -MData::Dump -wE "my %h = (A => 'a'); if (exists 
+$h{B}{C}) { say 'yes'; }; dd %h;"
("B", {}, "A", "a")

 0:33 >perl -Mstrict -MData::Dump -wE "no autovivification; my %h = (A
+ => 'a'); if (exists $h{B}{C}) { say 'yes'; }; dd %h;"
("A", "a")

 0:33 >
[download]

— as explained in the documentation for the exists function. So, as hippo says, using no autovivification; is the safest option.

Hope that helps,