Header File 

stdlib.h  

Category 

Math Routines 

Prototype 

long _lrand(void); 

Description 

_lrand is the long random number generator function. _rand uses a multiplicative congruential random number generator with period 2^64 to return successive pseudo-random numbers in the range from 0 to 2^31 - 1. 

The generator is reinitialized by calling srand with an argument value of 1. It can be set to a new starting point by calling srand with a given seed number.