c++ - Assigning values to enum -

while doing review of older code, notice following 2 strange constructions using enum (two different files/classes/namespaces, putting them here):

enum firstenum    {     a_choice    ,another_choice=1    ,yet_some_other_choice    };  enum secondenum    {     first_choice    ,second_choice    ,third_choice    ,default_choice=second_choice    }; 

i think both constructions wrong.

the first 1 assigns value 1 of choices, not others, meaning things might go wrong if new choices added.

in second case, end 2 enumeration elements having same underlying value.

is there reason why c++ standard allows both constructions?

(using visual studio 2010)

the first 1 assigns value 1 of choices, not others, meaning things might go wrong if new choices added.

i don't know mean "go wrong". it's well-defined if don't specify value enumerator, value 1 more previous (or zero, if it's first).

in second case, end 2 enumeration elements having same underlying value.

yes do. wrong if enumerations supposed set of unique values (in c++) aren't.

is there reason why c++ standard allows both constructions?

because, in c++, enumeration way declare set of related, named, constant values. doesn't try restrict values can take.