shlublu::Random Namespace Reference

Typedefs
using	Engine = std::mt19937_64
	Engine that is used by all Random functions.

Functions
template<typename T >
T	random (T min, T max)
	Returns a number from a given range. More...
template<typename T >
T	random (T min, T max, T step)
	Returns a number from a given range and rounded following a given step. More...
template<typename T >
T	randomUnit ()
	Returns a number from a unitary range. More...
template<typename T >
T	randomRelativeUnit ()
	Returns a number from a relative unitary range. More...
template<typename T >
bool	probability (T p)
	Returns a boolean depending on a probability. More...
template<typename T >
bool	likelihood (T chance, T total)
	Returns a boolean depending on the likelihood of an event. More...
bool	tossACoin ()
	Returns a boolean depending on a probability equal to 1/2. More...

Detailed Description

Set of helper functions intended to make usual operations easier. These functions are based on the standard random header and use a std::mt19937_64 engine. Distribution is std::uniform_real_distribution for real types and std::uniform_int_distribution for integral types.

The engine is initialized automatically. There is no need (and no way) to seed it with a timer or anything.

Function Documentation

random() [1/2]

template<typename T >

T shlublu::Random::random	(	T	min,
		T	max
	)

Returns a number from a given range.

The returned number belongs to the following range:

• [min, max) for real numbers
• [min, max] for integers

Template Parameters

T	the type of min, max and the returned value. This type should be arithmetic.

Parameters

min	the minimal value of the range
max	the maximal value of the range, included for integers and excluded for real numbers. It should be strictly greater than min.

Returns

a pseudo-random number in the range defined by min and max

Exceptions

std::invalid_argument

if min > max

Example

std::cout << Random::random(-5.0, 5.0) << std::endl;  // For example: 2.58067

random() [2/2]

template<typename T >

T shlublu::Random::random	(	T	min,
		T	max,
		T	step
	)

Returns a number from a given range and rounded following a given step.

The returned number belongs to the following range:

• [min, max) for real numbers
• [min, max] for integers

It is rounded to the nearest step.

Template Parameters

T	the type of min, max, step and the returned value. This type should be arithmetic.

Parameters

min	the minimal value of the range
max	the maximal value of the range, included for integers and excluded for real numbers. It should be strictly greater than min.
step	the rounding step. It must be lower than the amplitude of the range.

Returns

a pseudo-random number in the range defined by min and max and rounded to the nearest step.

Exceptions

std::invalid_argument

if step is negative or null, if step is greater than the amplitude of the range, or if min >= max

Example

std::cout << Random::random(-5.0, 5.0, 0.25) << std::endl; // For example: -3.75

randomUnit()

template<typename T >

T shlublu::Random::randomUnit

(

)

Returns a number from a unitary range.

Depending on T, the returned value:

• is an element of [0, 1) for real numbers
• is either 0 or 1 for integers

Template Parameters

T	the type of the returned value. This type should be arithmetic.

Returns

a pseudo-random number in the range defined by 0 and 1

Example

std::cout << Random::randomUnit<double>() << std::endl; // For example: 0.579902

randomRelativeUnit()

template<typename T >

T shlublu::Random::randomRelativeUnit

(

)

Returns a number from a relative unitary range.

Depending on T, the returned value:

• is an element of [-1, 1) for real numbers
• is either -1, 0 or 1 for integers

Template Parameters

T	the type of the returned value. This type should be arithmetic and signed.

Returns

a pseudo-random number in the range defined by -1 and 1

Example

std::cout << Random::randomRelativeUnit<double>() << std::endl; // For example: -0.926407

probability()

template<typename T >

bool shlublu::Random::probability

(

T

p

)

Returns a boolean depending on a probability.

This function has a probability of:

• p to return true
• 1 - p ti return false

Template Parameters

T	the type of the returned value. This type should be real.

Parameters

p	the probability of returning true. It should be in the range [0, 1]

Returns

true or false depending on a pseudo-random number

Exceptions

std::invalid_argument

if p is out of the range [0, 1]

Example

std::cout << (Random::probability(0.6) ? "yes" : "no") << std::endl; // For example: "yes"

likelihood()

template<typename T >

bool shlublu::Random::likelihood	(	T	chance,
		T	total
	)

Returns a boolean depending on the likelihood of an event.

This function has a chance out of total chance to return true. It returns false otherwise.

Template Parameters

T	the type of the returned value. This type should be integral.

Parameters

chance	the numberator of the chance
total	the denominator of the chance

Returns

true or false depending on a pseudo-random number

Exceptions

std::invalid_argument

if T is signed and chance is negative or if chance > total

Example

std::cout << (Random::likelihood(3, 11) ? "yes" : "no") << std::endl; // For example: "no"

tossACoin()

bool shlublu::Random::tossACoin

(

)

Returns a boolean depending on a probability equal to 1/2.

Returns

true or false depending on a pseudo-random number

Example

std::cout << (Random::tossACoin() ? "heads" : "tails") << std::endl; // For example: "heads"