Return multiple values

Return multiple values is a draft programming task. It is not yet considered ready to be promoted as a complete task, for reasons that should be found in its talk page.

Show how to return more than one value from a function.

Factor

With stack-oriented languages like Factor, a function returns multiple values by pushing them on the data stack. For example, this word */ pushes both x*y and x/y.

<lang factor>USING: io kernel math prettyprint ; IN: script

*/ ( x y -- x*y x/y )

   [ * ] [ / ] 2bi ;

15 3 */

[ "15 * 3 = " write . ] [ "15 / 3 = " write . ] bi*</lang>

Its stack effect declares that */ always returns 2 values. To return a variable number of values, a word must bundle those values into a sequence (perhaps an array or vector). For example, factors (defined in math.primes.factors and demonstrated at Prime decomposition#Factor) returns a sequence of prime factors.

Go

Functions can return multiple values in Go:

<lang go>func addsub(x, y int) (int, int) {

 return x + y, x - y

}</lang>

Or equivalently using named return style:

<lang go>func addsub(x, y int) (sum, difference int) {

 sum = x + y
 difference = x - y
 return

}</lang>

You can assign to a comma-separated list of targets:

<lang go>sum, difference := addsub(33, 12) fmt.Printf("33 + 12 = %d\n", sum) fmt.Printf("33 - 12 = %d\n", difference)</lang>

J

To return multiple values in J, you return an array which contains multiple values. Since the only data type in J is array, this is sort of like asking how to return only one value in another language.

<lang j> 1 2+3 4 4 6</lang>

PHP

Every function returns one value. The conventional way to return multiple values is to bundle them into an array.

<lang php>function addsub($x, $y) {

 return array($x + $y, $x - $y);

}</lang>

You can use the list() construct to assign to multiple variables:

<lang php>list($sum, $difference) = addsub(33, 12); echo "33 + 12 = $sum\n"; echo "33 - 12 = $difference\n";</lang>

Pike

multiple values are returned through an array. an array can be assigned to separate variables. <lang Pike> array(int) addsub(int x, int y) {

   return ({ x+y, x-y });

}

[int z, int w] = addsub(5,4); </lang>

Python

Every function returns one value. The conventional way to return multiple values is to bundle them into a tuple.

<lang python>def addsub(x, y):

 return x + y, x - y</lang>

(Note that parentheses are not necessary for a tuple literal in Python.)

You can assign to a comma-separated list of targets:

<lang python>sum, difference = addsub(33, 12) print "33 + 12 = %s" % sum print "33 - 12 = %s" % difference</lang>

Ruby

Every function returns one value. The conventional way to return multiple values is to bundle them into an Array.

Use an array literal:

<lang ruby>def addsub(x, y)

 [x + y, x - y]

end</lang>

Or use return with 2 or more values:

<lang ruby>def addsub(x, y)

 return x + y, x - y

end</lang>

(With at least 2 values, return makes a new Array. With 1 value, return passes the value, without making any Array. With 0 values, return passes nil.)

Assignment can split the Array into separate variables.

<lang ruby>sum, difference = addsub(33, 12) puts "33 + 12 = #{sum}" puts "33 - 12 = #{difference}"</lang>