Question

For some reason I had this idea that C and C++ worked like this:

int foo[10] = {57};
for (int i=0; i<10; ++i)
    assert (foo[i] == 57);

Turns out the remaining ints are initialized to 0, not 57. Where did I get this idea? Was this true at one point? Was it ever true for structure initializer lists? When did arrays and structures neatly and correctly start initializing themselves to 0 values when assigned to = {} and = {0}? I always thought they’d initialize to garbage unless explicitly told otherwise.

Answer 1

It’s been this way forever, as long as initializers existed. C89 says:

If there are fewer initializers in a list than there are members of an
aggregate, the remainder of the aggregate shall be initialized
implicitly the same as objects that have static storage duration.