Perl 5 version 24.1 documentation
Returns a random fractional number greater than or equal to
0and less than the value of EXPR. (EXPR should be positive.) If EXPR is omitted, the value
1is used. Currently EXPR with the value
0is also special-cased as
1(this was undocumented before Perl 5.8.0 and is subject to change in future versions of Perl). Automatically calls srand unless srand has already been called. See also srand.
returns a random integer between
(Note: If your rand function consistently returns numbers that are too large or too small, then your version of Perl was probably compiled with the wrong number of RANDBITS.)
rand is not cryptographically secure. You should not rely on it in security-sensitive situations. As of this writing, a number of third-party CPAN modules offer random number generators intended by their authors to be cryptographically secure, including: Data::Entropy, Crypt::Random, Math::Random::Secure, and Math::TrulyRandom.