The idiomatic way to get a pointer to one past the end of an array x with element-type foo is x + sizeof x / sizeof *x which is equivalent to (foo *)

The idiomatic way to get a pointer to one past the end of an array x with element-type foo is x + sizeof x / sizeof *x which is equivalent to (foo *)((char *)x + sizeof x) whereas x + sizeof x is equivalent to (foo *)((char *)x + sizeof (foo) * sizeof x)) The expression &x + 1 is not idiomatic as it has the type pointer-to-array-of-foo instead of pointer-to-foo. As to your final question: Parameter declarations discard the size of array types - they are actually pointer-declarations in disguise. To enforce a fixed array size, you need to declare a parameter of type pointer-to-array, eg void bar(int (*arg)[42]); which you'd have to call like this: int x[42] = { 0 }; bar(&x);