How to Properly Initialize Static String Variables in C Classes?

Initializing Static Strings in C Classes

When declaring member functions and variables within a class, the scope and accessibility become important considerations. In case you encounter a situation where some member functions are not directly accessing class objects and you decide to make them static, you may also need to modify the declarations of the variables they access.

Issue: Initializing Static String Variables

If you have string variables like the ones below within a class:

string RE_ANY = "([^\n]*)";
string RE_ANY_RELUCTANT = "([^\n]*?)";

Making them static const variables ensures they remain unchanged, but can lead to issues with initialization. The compiler may complain that static constant integral variables can only be initialized within a class.

Solution: External Initialization

As a workaround, you can initialize these static string variables outside the class in a source file. For example:

// Within the class
class Thing {
    static string RE_ANY;
    static string RE_ANY_RELUCTANT;
};

// In a source file
string Thing::RE_ANY = "([^\n]*)";
string Thing::RE_ANY_RELUCTANT = "([^\n]*?)";

Caution: Distinguishing Static and Const Functions

It's crucial to note that you should not make the member functions accessing these strings static, as they still need to access class members. Instead, consider making them const functions, which prevents them from modifying class members. This maintains the required association between functions and class objects while ensuring immutability.

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