arc4random_buf3

Usage

#include <stdlib.h>

Library

Standard C library (libc, -lc)

Overview

These functions give cryptographically-secure pseudorandom numbers.

arc4random() returns a uniformly-distributed value.

arc4random_uniform() returns a uniformly-distributed value less than upper_bound (see BUGS).

arc4random_buf() fills the memory pointed to by buf, with n bytes of pseudorandom data.

The rand(3) and drand48(3) families of functions should only be used where the quality of the pseudorandom numbers is not a concern and there's a need for repeatability of the results. Unless you meet both of those conditions, use the arc4random() functions.

Return value

arc4random() returns a pseudorandom number.

arc4random_uniform() returns a pseudorandom number less than upper_bound for valid input, or 0 when upper_bound is invalid.

Attributes

For an explanation of the terms used in this section, see attributes(7).