C language : How to generate random Number in every launch of program?

Question

It's pretty difficult for me to do that... I tried the rand fonction but nothing... Any help?

Answer 1

Using the rand() function is just one side of the coin:

https://en.cppreference.com/w/c/numeric/random/rand

You also need to seed it with a start value before using it, otherwise you will get the same results. This is done via srand():

https://en.cppreference.com/w/c/numeric/random/srand

A typical value for srand() is generated with the help of the time() function, i.e.

srand( time ( 0 ) );

This is necessary because pseudo-random number generation is basically just a numerical algorithm; if you start with the same number, you get the exact same result. Therefore, you need a variable seed to get different numbers every launch.

Answer 2

I see... Thanks for the tip. I'll try it