##
table of contents

Random(3) | OCaml library | Random(3) |

# NAME¶

Random - Pseudo-random number generators (PRNG).

# Module¶

Module Random

# Documentation¶

Module **Random**

: **sig end**

Pseudo-random number generators (PRNG).

## Basic functions¶

*val init* : **int -> unit**

Initialize the generator, using the argument as a seed. The same seed will always yield the same sequence of numbers.

*val full_init* : **int array -> unit**

Same as **Random.init** but takes more data as seed.

*val self_init* : **unit -> unit**

Initialize the generator with a random seed chosen in a
system-dependent way. If **/dev/urandom** is available on the host
machine, it is used to provide a highly random initial seed. Otherwise, a
less random seed is computed from system parameters (current time, process
IDs).

*val bits* : **unit -> int**

Return 30 random bits in a nonnegative integer.

**Before3.12.0** used a different algorithm (affects all the
following functions)

*val int* : **int -> int**

**Random.int bound** returns a random integer between 0
(inclusive) and **bound** (exclusive). **bound** must be greater than
0 and less than 2^30.

*val full_int* : **int -> int**

**Random.full_int bound** returns a random integer between 0
(inclusive) and **bound** (exclusive). **bound** may be any positive
integer.

If **bound** is less than 2^30, **Random.full_int bound** is
equal to **Random.int** **bound** . If **bound** is greater than
2^30 (on 64-bit systems or non-standard environments, such as JavaScript),
**Random.full_int** returns a value, where **Random.int** raises
**Invalid_argument** .

**Since** 4.13.0

*val int32* : **Int32.t -> Int32.t**

**Random.int32 bound** returns a random integer between 0
(inclusive) and **bound** (exclusive). **bound** must be greater than
0.

*val nativeint* : **Nativeint.t -> Nativeint.t**

**Random.nativeint bound** returns a random integer between 0
(inclusive) and **bound** (exclusive). **bound** must be greater than
0.

*val int64* : **Int64.t -> Int64.t**

**Random.int64 bound** returns a random integer between 0
(inclusive) and **bound** (exclusive). **bound** must be greater than
0.

*val float* : **float -> float**

**Random.float bound** returns a random floating-point number
between 0 and **bound** (inclusive). If **bound** is negative, the
result is negative or zero. If **bound** is 0, the result is 0.

*val bool* : **unit -> bool**

**Random.bool ()** returns **true** or **false** with
probability 0.5 each.

*val bits32* : **unit -> Int32.t**

**Random.bits32 ()** returns 32 random bits as an integer
between **Int32.min_int** and **Int32.max_int** .

**Since** 4.14.0

*val bits64* : **unit -> Int64.t**

**Random.bits64 ()** returns 64 random bits as an integer
between **Int64.min_int** and **Int64.max_int** .

**Since** 4.14.0

*val nativebits* : **unit -> Nativeint.t**

**Random.nativebits ()** returns 32 or 64 random bits
(depending on the bit width of the platform) as an integer between
**Nativeint.min_int** and **Nativeint.max_int** .

**Since** 4.14.0

## Advanced functions¶

The functions from module **Random.State** manipulate the
current state of the random generator explicitly. This allows using one or
several deterministic PRNGs, even in a multi-threaded program, without
interference from other parts of the program.

*module State :* **sig end**

*val get_state* : **unit -> State.t**

Return the current state of the generator used by the basic functions.

*val set_state* : **State.t -> unit**

Set the state of the generator used by the basic functions.

2024-03-14 | OCamldoc |