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Since I don't think the C standard says anything explicitly about cases like this, it is probably undefined behavior, under the "not mentioned in the standard" variety. If something isn't mentioned...
Answer
#1: Initial revision
by
Lundin
·
2023-01-23T11:00:49Z (over 1 year ago)
Since I don't think the C standard says anything explicitly about cases like this, it is probably undefined behavior, under the "not mentioned in the standard" variety. If something isn't mentioned, it is per definition undefined and not well-defined. The closest thing might be the somewhat unclear rules about "effective type" and "strict aliasing" in 6.5: "For all other accesses to an object having no declared type, the effective type of the object is simply the type of the lvalue used for the access." Everything returned from `malloc` has no declared type. This doesn't mention anything about arrays, except that we can make an access through an "aggregate" (array or struct) that contains the effective type as one of its members. However, nothing in the standard mentions what happens when you allocate too little space. As far as `malloc` is concerned, you have allocated an object with size `50 * sizeof(int)` bytes, which has no declared type.