Why Can't I Directly Assign Arrays in C and C , But I Can Within Structs?

Array Assignment in C and C

C and C allow memberwise assignment of arrays within structs but not in general. This behavior is a result of the historical evolution of the languages.

Initially, arrays in C were modeled as pointers in memory, known as a "cooked arrays." When structures were introduced, arrays within structures were treated differently to ensure memory safety. This allowed arrays to be assigned memberwise within structs without compromising compatibility with existing code.

In contrast, assignment of arrays outside of structs was not supported in C's original design. This was due to concerns about pointer rebasing and the lack of size information for arrays declared as function parameters. To avoid introducing bugs and compatibility issues, explicit assignment using memcpy was preferred.

However, as noted by Luther Blissett, C's specification regarding structure assignment explicitly allows memberwise assignment of contained arrays. This was an unintended side effect of the design, but it was embraced as a way to facilitate data copying within structs without breaking established patterns.

Therefore, the support for memberwise assignment of arrays within structs but not generally is a legacy of C's early design decisions and the subsequent evolution of the language, resulting in a distinction between arrays embedded within structures and arrays used independently.

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