ptrdiff_t
(3type)count of elements or array index
#include <stddef.h> typedef /* ... */ ptrdiff_t;
LIBRARY
DESCRIPTION
Used for a count of elements, or an array index. It is the result of subtracting two pointers. It is a signed integer type capable of storing values in the range [PTRDIFF_MIN, PTRDIFF_MAX].
The length modifier for ptrdiff_t for the printf(3) and the scanf(3) families of functions is t, resulting commonly in %td or %ti for printing ptrdiff_t values.