int
Returns a random int i such that minInt(T) <= i <= maxInt(T).
i is evenly distributed.
Function parameters
Parameters
Fast unbiased random numbers.
Types
- DefaultPrng
- Fast unbiased random numbers.
- DefaultCsprng
- Cryptographically secure random numbers.
Functions in this namespace
Functions
- bytes
- Read random bytes into the specified buffer until full.
- enumValue
- Returns a random value from an enum, evenly distributed.
- enumValueWithIndex
- Returns a random value from an enum, evenly distributed.
- int
- Returns a random int `i` such that `minInt(T) <= i <= maxInt(T)`.
- uintLessThanBiased
- Constant-time implementation off `uintLessThan`.
- uintLessThan
- Returns an evenly distributed random unsigned integer `0 <= i < less_than`.
- uintAtMostBiased
- Constant-time implementation off `uintAtMost`.
- uintAtMost
- Returns an evenly distributed random unsigned integer `0 <= i <= at_most`.
- intRangeLessThanBiased
- Constant-time implementation off `intRangeLessThan`.
- intRangeLessThan
- Returns an evenly distributed random integer `at_least <= i < less_than`.
- intRangeAtMostBiased
- Constant-time implementation off `intRangeAtMostBiased`.
- intRangeAtMost
- Returns an evenly distributed random integer `at_least <= i <= at_most`.
- float
- Return a floating point value evenly distributed in the range [0, 1).
- floatNorm
- Return a floating point value normally distributed with mean = 0, stddev = 1.
- floatExp
- Return an exponentially distributed float with a rate parameter of 1.
- shuffle
- Shuffle a slice into a random order.
- shuffleWithIndex
- Shuffle a slice into a random order, using an index of a
- weightedIndex
- Randomly selects an index into `proportions`, where the likelihood of each
- limitRangeBiased
- Convert a random integer 0 <= random_int <= maxValue(T),
Source
Implementation
pub fn int(r: Random, comptime T: type) T {
const bits = @typeInfo(T).int.bits;
const UnsignedT = std.meta.Int(.unsigned, bits);
const ceil_bytes = comptime std.math.divCeil(u16, bits, 8) catch unreachable;
const ByteAlignedT = std.meta.Int(.unsigned, ceil_bytes * 8);
var rand_bytes: [ceil_bytes]u8 = undefined;
r.bytes(&rand_bytes);
// use LE instead of native endian for better portability maybe?
// TODO: endian portability is pointless if the underlying prng isn't endian portable.
// TODO: document the endian portability of this library.
const byte_aligned_result = mem.readInt(ByteAlignedT, &rand_bytes, .little);
const unsigned_result: UnsignedT = @truncate(byte_aligned_result);
return @bitCast(unsigned_result);
}