N.B. nonzero bitpattern nullptrs are common in C++ for pointer-to-member s, which are typically implemented as an offset from the start of the structure - with

N.B. nonzero bitpattern nullptrs are common in C++ for pointer-to-member s, which are typically implemented as an offset from the start of the structure - with an all-0 bitpattern being a valid non-null pointer to the first member of said structure. struct S { int i; }; int S::*a = &S::i; // probably 0 under the hood int S::*b = nullptr; // probably -1 under the hood int S::*c = 0; // probably -1 under the hood (no typo!) Consider using brace initializers as an ergonomic alternative: struct S d = { 0 }; struct S e = {}; /* as of C23 or C++ */