difference between rand() and srand()...????

Answer 1

rand() returns a 'random' number. srand() is used to seed the RNG algorithm. Check out how seeding works:

https://code.sololearn.com/cMUCJqFL1X65/?ref=app

Answer 2

rand() returns a random number
srand() sets the seed to get the random numbers
See ‎https://en.m.wikipedia.org/wiki/Linear_congruential_generator