How to get a larger random number from the c function rand()

Question

I am in a coding environment where I only have access to some most basic c functions. #include\'ing other lib is not feasible.

In this environment, I can call rand()

Answer 1

rnum = (rand() << 15) | rand() might be faster, but if you need good quality random numbers you should look for an external library. Built-in random functions are generally adequate only for the simplest applications.