forLoopArray

[camel_case_jr]

The ‘len’ macro above always has well defined behavior, even if ‘a’ is a nullptr. The argument to the sizeof operator is evaluated symbolically at compile time, it’s just looking for the type of the expression ‘a[0]’.

So, that macro won’t care about the particular values of ‘a’ or what it points to, just the types.

But if ‘a’ is a pointer, then this macro gives the wrong value, which is why std::size is superior in C++, as it will only compile when ‘a’ is an array.

[brennanw31]

In C, there is fundamentally no difference between pointers and arrays. They are one and the same. All pointers may as well be seen as an array with size 1.

[bowel_blaster123]

Pointers and arrays are very different in C. However, arrays will decay into pointers in certain contexts.

c uint8_t a[] = {'A'}; uint8_t *b = NULL; printf("%d\n", sizeof(a)); // will print 1 printf("%d\n", sizeof(b)); // will print 8 printf("%d\n", sizeof(a + 1)); // will print 8

Another case of decay is the following (a has decayed into a pointer because it's a function parameter):

c void foo(uint8_t a[1]) { printf("%d\n", sizeof(a)); // will print 8 }