Why Doesn't C Allow Anonymous Structs?

Anonymous Structs in C : Why the Standard Says No

C compilers may allow anonymous structs and unions as an aid to code readability, but the standard explicitly prohibits anonymous structs. Understanding the rationale behind this decision is key for effective C programming.

The standard permits anonymous unions because they exist in C. However, anonymous structs are not supported in C, so C has no need to include them for compatibility reasons. Unlike anonymous unions, which allow convenient access to data in different formats, anonymous structs serve a limited purpose in C .

The example provided, where a struct contains three floats accessible by both member variables and an array, raises concerns about undefined behavior. C 's strict type system disallows writing to one union member and then reading from another, which could occur with anonymous structs like the example shown.

Instead of anonymous structs, C offers alternative solutions for managing data structures. Custom types, such as the one demonstrated in the answer, provide similar functionality with safety and readability.

Through this discussion, we gain insight into the design choices underlying C . The standard's adherence to compatibility and its focus on well-defined behavior guide the inclusion or exclusion of features like anonymous structs. By understanding these principles, developers can make informed choices about which language constructs to employ for their programming needs.

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