How Do I Properly Define Static Const Integer Class Members in C ?

Defining Static Const Integer Members in Class Definitions: An Exploration

C allows the declaration of static const integer members within class definitions. However, it's crucial to understand the distinction between initialization and definition in this context.

In the example code provided:

class test
{
public:
    static const int N = 10;
};

The declaration of N within the class initializes it with a value of 10. However, this is not equivalent to a definition. To resolve the linker error encountered, a separate definition of N is required outside the class definition. This can be achieved through a namespace scope definition, such as:

const int test::N = 10;

Alternately, the constexpr keyword can be used to both declare and define static const integer members in a single step, eliminating the need for a separate definition:

class test
{
public:
    static constexpr int N = 10;
};

In the case where std::min is called, it expects parameters passed by reference. As N is declared as a static const integer, it needs to be defined to pass the reference requirement. Commenting out the call to std::min allows the code to compile because the definition of N is no longer necessary, although it is still referenced.

In summary, while C allows the initialization of static const integer members within class definitions, a separate definition is necessary for referencing the value. This can be achieved through a namespace scope definition or by using the constexpr keyword.

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