Random number generation in C++ is provided by the
<random> header. This header defines random devices, pseudo-random generators and distributions.
Random devices return random numbers provided by operating system. They should either be used for initialization of pseudo-random generators or directly for cryptographic purposes.
Pseudo-random generators return integer pseudo-random numbers based on their initial seed. The pseudo-random number range typically spans all values of an unsigned type. All pseudo-random generators in the standard library will return the same numbers for the same initial seed for all platforms.
Distributions consume random numbers from pseudo-random generators or random devices and produce random numbers with necessary distribution. Distributions are not platform-independent and can produce different numbers for the same generators with the same initial seeds on different platforms.