Integer Random Numbers (GNU MP 6.3.0)
Description: How to install and use the GNU multiple precision arithmetic library, version 6.3.0.

### 5.13 Random Number Functions ¶

The random number functions of GMP come in two groups; older functions that rely on a global state, and newer functions that accept a state parameter that is read and modified. Please see the Random Number Functions for more information on how to use and not to use random number functions.

Function: `void` mpz_urandomb `(mpz_t rop, gmp_randstate_t state, mp_bitcnt_t n)` ¶

  Generate a uniformly distributed random integer in the range 0 to 2n-1, inclusive.

  The variable state must be initialized by calling one of the `gmp_randinit` functions (Random State Initialization) before invoking this function.

Function: `void` mpz_urandomm `(mpz_t rop, gmp_randstate_t state, const mpz_t n)` ¶

  Generate a uniform random integer in the range 0 to n-1, inclusive.

  The variable state must be initialized by calling one of the `gmp_randinit` functions (Random State Initialization) before invoking this function.

Function: `void` mpz_rrandomb `(mpz_t rop, gmp_randstate_t state, mp_bitcnt_t n)` ¶

  Generate a random integer with long strings of zeros and ones in the binary representation. Useful for testing functions and algorithms, since this kind of random numbers have proven to be more likely to trigger corner-case bugs. The random number will be in the range 2n-1 to 2n-1, inclusive.

  The variable state must be initialized by calling one of the `gmp_randinit` functions (Random State Initialization) before invoking this function.

Function: `void` mpz_random `(mpz_t rop, mp_size_t max_size)` ¶

  Generate a random integer of at most max_size limbs. The generated random number doesn’t satisfy any particular requirements of randomness. Negative random numbers are generated when max_size is negative.

  This function is obsolete. Use `mpz_urandomb` or `mpz_urandomm` instead.

Function: `void` mpz_random2 `(mpz_t rop, mp_size_t max_size)` ¶

  Generate a random integer of at most max_size limbs, with long strings of zeros and ones in the binary representation. Useful for testing functions and algorithms, since this kind of random numbers have proven to be more likely to trigger corner-case bugs. Negative random numbers are generated when max_size is negative.

  This function is obsolete. Use `mpz_rrandomb` instead.