Strongly Typed Enum

Jumana Bohra — Sun, 29 Mar 2020 05:18:49 +0000

Enum is a user-defined datatype. It is a set of integral constants termed as enumerators.

Enum has a limitation. Two enum in a scope cannot have same enumerators. To remove this limitation, C++11 introduced Strongly Typed Enum. Strongly Typed Enum allows you to have enumerators which can be redundant from any other enum. In declaration, a keyword 'class' is added after enum to specify it is a strongly typed enum.

syntax: enum class user-definedDatatype { ....};

Strongly typed enum, provides flexibility at the cost that it has to be used with scope resolution. The surrounding gets corrupted because of redundant enumerators. Hence it is a compilation error to declare or use strongly typed enum without scope resolution. Attached snippet will make it clear

Snippet of the same code to copy and try:

using namespace std;
int main(){
enum class colors { red, blue, aquamarine, yellow };
enum class PrimaryColors { green, blue, red };
enum SecondaryColors { magenta, yellow, cyan };
enum trafficlights { red, /*yellow, */ green }; //yellow is redundant
SecondaryColors sc = yellow;
// colors r = red;
colors r = colors::red;
}

Something I learnt more about const keyword

Jumana Bohra — Fri, 06 Mar 2020 05:03:06 +0000

const keyword has multiple usages in c++ as per the position of the keyword. While going through my project code const captured my attention again, being placed at the end of function declaration. Something like this:

ReturnType FunctionName (FormalParameters...) const;

While discovering its use case I found it quite helpful. This type of function is called a "const function". Such function restricts changing it's class variable inside it. It is a compilation error for const function to change it's member class variable.

Well the restriction can be loosened by the storage class specifier mutable. However it can be used efficiently for getter methods.

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Strongly Typed Enum

Something I learnt more about const keyword