Correct way to use scanf / printf (and family) with fixed size types?

Question

Reading this SO question, I started wondering - what is the correct way to use scanf/printf (and family) with fixed size types?

For example

Answer 1

The correct way is to use inttypes.h which defines standard macros for printf family and the scanf family, e.g.

printf ("%" PRId16, short_int);
scanf ("%" SCNd16, &short_int);

Answer 2

The inttypes.h header file contains macros that define the correct format specifiers for fixed-width integers defined in stdint.h. For example, the type specifier for printf() and int16_t is the macro named PRId16. Example:

int16_t x;
scanf("%" SCNd16, &x);

printf("You have entered: %" PRId16 "\n", x);