Why can I assign a string literal whose length is less than the array itself?

Question

I'm a bit baffled that this is allowed:

char num[6] = "a";

What is happening here? Am I assigning a pointer to the array or copying the literal values into the array (and therefore I'm able to modify them later)?

Answer 1

1. Why can I assign a string literal less than the array itself? What is happening here?

This is well defined. When initialize character arrays with string literal,

If the size of the array is specified and it is larger than the number of characters in the string literal, the remaining characters are zero-initialized.

So,

char num[6] = "a";
// equivalent to char num[6] = {'a', '\0', '\0', '\0', '\0', '\0'};

2. Am I assigning a pointer to the array or copying the literal values into the array (and therefore I'm able to modify them later)?

The value will be copied, i.e. the elements of the array will be initialized by the chars of the string literal (including '\0').

String literals can be used to initialize character arrays. If an array is initialized like char str[] = "foo";, str will contain a copy of the string "foo".

Successive characters of the string literal (which includes the implicit terminating null character) initialize the elements of the array.