Why does the arrow (->) operator in C exist?
The article discusses the rationale behind the arrow operator (->) in the C programming language. It explains how C's evolution from earlier languages influenced its treatment of pointers and structures. The piece highlights the inconsistency in how arrays and structs are handled in terms of dereferencing and type information.
- ▪The arrow operator is used to access members of a structure through a pointer.
- ▪C's treatment of arrays and structs differs due to its historical evolution from BCPL and other languages.
- ▪The article questions why C does not apply similar dereferencing logic to structs as it does to arrays.
Opening excerpt (first ~120 words) tap to expand
This doesn’t really answer the question. In order to dereference a pointer, the * operator needs to know the type of its operand. So C of that era had enough type information to know whether a variable was a pointer or not, and what type it pointed to. So (in theory) it also had enough type information to know whether . should offset (if the left operand is a struct type) or indirect (otherwise). But in practice it didn’t pay attention to types in that manner, because of the way it gradually evolved from BCPL via B and NB. This weirdness is also (weirdly) related to C’s weird treatment of arrays that decay to pointers. In BCPL, when you declare v[10] you get 10 slots for the array elements but also a -1th slot containing pointer to the start of the array (ie, v == &v + 1).
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Excerpt limited to ~120 words for fair-use compliance. The full article is at Lobsters.
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