In the declaration char letter = 'x'; the initialization expression 'x', which for historical reasons is of type int in C, is implicitly converted to the

In the declaration char letter = 'x'; the initialization expression 'x', which for historical reasons is of type int in C, is implicitly converted to the type of the object. `letter` is a `char` because you defined it that way. If you had written int letter = 'x'; that would be perfectly valid, and the conversion would be trivial (int to int). It's just like: double x = 42; `sizeof 42` might be 4 (sizeof (int)), but `sizeof x` will be the same as `sizeof (double)` (perhaps 8).