rand()

Question

why the rand() function used in a program returns the same numbers again and again? What is the meaning of "random" if they are every time the same ?

Answer 1

@Jay is correct. All these "random" numbers originate from the same built-in RNG algorithm which requires to be seeded with a different value every time the program runs. By including <ctime>, time(0) returns the system time (time in seconds since 01/01/1970), which is ever-changing and suitable to be used as a seed.

Answer 2

you forgot to seed using srand.

see the lessons here for a refresher on using rand.

srand(time(0)); // use this before you call rand