History of Idiom 15 > diff from v24 to v25

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Version 24

2015-09-05, 15:23:16

Version 25

2015-10-29, 14:05:12

Idiom #15 Pick uniformly a random integer in [a..b]

Pick a random integer greater than or equals to a, inferior or equals to b. Precondition : a < b.

Idiom #15 Pick uniformly a random integer in [a..b]

Pick a random integer greater than or equals to a, inferior or equals to b. Precondition : a < b.

Clojure

Clojure

Code

( + a (rand-int (- b a)))

Code

( + a (rand-int (- b a)))

Doc URL

http://clojuredocs.org/clojure.core/rand-int

Doc URL

http://clojuredocs.org/clojure.core/rand-int

Haskell

Haskell

Imports

import System.Random

Imports

import System.Random

Code

let pick (a, b) = randomRIO (a, b) :: IO Integer
 in pick (1, 6) >>= print

Code

let pick (a, b) = randomRIO (a, b) :: IO Integer
 in pick (1, 6) >>= print

Doc URL

http://hackage.haskell.org/package/random/docs/System-Random.html

Doc URL

http://hackage.haskell.org/package/random/docs/System-Random.html

Code

rand($a, $b)

Code

rand($a, $b)

Doc URL

http://php.net/manual/en/function.rand.php

Doc URL

http://php.net/manual/en/function.rand.php

Code

function pick(a, b) {
    return a + Math.floor(Math.random() * (b - a + 1));
}

Code

function pick(a, b) {
    return a + Math.floor(Math.random() * (b - a + 1));
}

Comments bubble

You have to build it from a floating-point random number. It is important to use floor , not round .

Comments bubble

You have to build it from a floating-point random number. It is important to use floor , not round .

Origin

http://stackoverflow.com/a/10134261/871134

Origin

http://stackoverflow.com/a/10134261/871134

Imports

import "math/rand"

Imports

import "math/rand"

Code

func pick(a,b int) int {
	return a + rand.Intn(b-a+1)
}

Code

func pick(a,b int) int {
	return a + rand.Intn(b-a+1)
}

Comments bubble

(b-a+1) is needed to have upper bound b included.

Comments bubble

(b-a+1) is needed to have upper bound b included.

Imports

#include <stdlib.h>

Imports

#include <stdlib.h>

Code

int pick(int a, int b)
{
	return a + rand() % (b - a);
}

Code

int pick(int a, int b)
{
	return a + rand() % (b - a);
}

Java

Java

Imports

import java.util.Random;

Imports

import java.util.Random;

Code

int pick(int a, int b){
	return a + new Random().nextInt(b - a + 1);
}

Code

int pick(int a, int b){
	return a + new Random().nextInt(b - a + 1);
}

Comments bubble

For performance, consider reusing the Random object.

(b-a+1) is needed to have upper bound b included.

Comments bubble

For performance, consider reusing the Random object.

(b-a+1) is needed to have upper bound b included.

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History of Idiom 15 > diff from v24 to v25

Version 24

Version 25

Idiom #15 Pick uniformly a random integer in [a..b]

Idiom #15 Pick uniformly a random integer in [a..b]

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