In a Korean government examination, (1) was a correct statement.
Choose the wrong statement for the following two-dimensional array in C:
int mat[3][4]={1,2,3,4,5,6};
(1) The value of mat[2][2] is 0.
I had been thinking that C does not fill integer arrays with 0’s, so I tried to look up the specification, but document was too big. This answer (screenshot below for quick viewing, full text is in the link) seems to be saying that incomplete initialisation is implied to be 0, but is it guaranteed by the C specification?
>Solution :
From the C Standard (6.7.9 Initialization):
19 The initialization shall occur in initializer list order, each
initializer provided for a particular subobject overriding any
previously listed initializer for the same subobject; all subobjects
that are not initialized explicitly shall be initialized implicitly
the same as objects that have static storage duration.
and
10 If an object that has automatic storage duration is not initialized
explicitly, its value is indeterminate. If an object that has static
or thread storage duration is not initialized explicitly, then:— if it has pointer type, it is initialized to a null pointer;
— if it has arithmetic type, it is initialized to (positive or
unsigned) zero;— if it is an aggregate, every member is initialized (recursively)
according to these rules, and any padding is initialized to zero bits;— if it is a union, the first named member is initialized
(recursively) according to these rules, and any padding is initialized
to zero bits;
So all elements of the array mat that are not initialized explicitly are initialized implicitly by zeroes.
int mat[3][4]={1,2,3,4,5,6};
As a result in the above declaration mat[2][2] is equal to 0.
Do I have passed the Korean government examination?:)