Use of format specifier %zu

Answer 1

%zu is used for `size_t` type
http://en.cppreference.com/w/cpp/types/size_t

See also
http://www.cplusplus.com/reference/cstdio/scanf/
http://www.cplusplus.com/reference/cstdio/printf/

Answer 2

Srishti Read the comments here in this lesson for various format specifiers
https://www.sololearn.com/learn/C/2912/

Answer 3

size_t type