What is the header file of srand() function

Answer 1

<cstdlib>

Answer 2

A call to the rand() function (header file stdlib.h), with no arguments, returns a fairly good approximation to a random integer in the range 0 to RAND_MAX (defined in stdlib.h). Thesrand() function sets its argument, which is of type int, as the seed for a new sequence of numbers to be returned by rand().

http://farside.ph.utexas.edu/teaching/329/lectures/node25.html