Home Accessibility Courses Twitter The Mouth Facebook Resources Site Map About Us Contact
 
20.9.2014 - We have just updated our course layouts and descriptions and added our 2015 schedule.

Returning multiple values from a function call in various languages - a comparison

I've always thought it a bit odd that you call a function with any number of parameters, and yet it returns a single value; in Java, C or C++ you declare a return type (void if there is not to be anything returned) and you are then constrained by that specification. There are, of course, other ways of returning data too. Most languages support some sort of global capability, or "call by reference" in which you can modify the incoming data and that alteration will also change the variable's contents as seen in the calling code. And in some languages such as Perl, special variables may be set within a function and the accessed outside.

But some languages do support multiple returns:

Ruby. If you return an array, and assign the result to more than one variable (in a comma separated list), the array will be unwrapped:
  smaller,larger = ben 10,20,30
See full code example [here]

Python. If you return a tuple, it can be split out into multuple variables:
  smaller,larger = ben(10,20,30)
See [here] - a previous article than includes a complete example

Perl. You can return a list (of several items) of a scalar from a sub, and you can use the misnamed wantarray function within the sub to determine the return type. You assign the returned value into a scalar or a list (remembering that assigning a list to a scalar will give you the length of the list!). There's an example in our course material [here] and you can assign the results to a named list of scalars if you wish:
  ($smaller,$larger) = ben(10,20,30)

PHP. If you return an array, you can assign it into a list function and store each of the returned members into its own variable:
  list($smaller, $larger) = ben(10,20,20);
You'll find this used in our real live global site index, for which we publish the source code (passwords changed!) [here]. There's a shorter example that uses this [here].

Before you start returning multiple values, though, think carefully. Should you be returning a single object instead?. A regular expression match in Perl returns a list of matched strings (if used in a list context). But in other languages (though you may have the option of multiple values back) you can also get back a single object from which you can request the elements that you need.
(written 2011-02-06, updated 2011-02-10)

 
Associated topics are indexed as below, or enter http://melksh.am/nnnn for individual articles
H109 - PHP - Input / Output
  [3424] Divide 10000 by 17. Do you get 588.235294117647, 588.24 or 588? - Ruby and PHP - (2011-09-08)
  [3029] PHP data sources - other web servers, large data flows, and the client (browser) - (2010-11-04)
  [2964] An introduction to file handling in programs - buffering, standard in and out, and file handles - (2010-09-21)
  [1780] Server overloading - turns out to be feof in PHP - (2008-09-01)
  [1442] Reading a file multiple times - file pointers - (2007-11-23)
  [1113] File and URL reading in PHP - (2007-03-20)
  [1096] Sample script - FTP to get a file from within PHP - (2007-03-01)
  [1094] PHP fread - truncated data - (2007-02-27)
  [997] Most recent file in a directory - PHP - (2006-12-18)
  [709] Handling huge data files in PHP - (2006-05-04)
  [653] Easy feed! - (2006-03-21)
  [616] printf - a flawed but useful function - (2006-02-22)
  [114] Relative or absolute milkman - (2004-11-10)

H308 - PHP - Searches, and search engines
  [3163] Twitter - the special use of @ # and http: in tweets - (2011-02-09)
  [2631] How to show a large result set page by page in PHP - (2010-02-11)
  [2166] Crossrefering documents with uniqueness and inconsistency issues - PHP proof of concept demo - (2009-05-10)
  [2137] Reaching the right people with your web site - (2009-04-23)
  [1735] Finding words and work boundaries (MySQL, Perl, PHP) - (2008-08-03)
  [1020] Parallel processing in PHP - (2007-01-03)

P303 - Perl - Miscellany
  [3012] Exception handling in Perl - using eval - (2010-10-23)
  [2877] Further more advanced Perl examples - (2010-07-19)
  [2876] Different perl examples - some corners I rarely explore - (2010-07-18)
  [2427] Operator overloading - redefining addition and other Perl tricks - (2009-09-27)
  [2219] Configuring httpd, or Tomcat, to run CGI scripts in Perl - (2009-06-05)

R104 - Ruby - Control Structures
  [3769] Muttable v immutable and implications - Ruby - (2012-06-20)
  [3620] Finding the total, average, minimum and maximum in a program - (2012-02-22)
  [3619] Ruby v Perl - a comparison example - (2012-02-21)
  [3422] Assigning values to variables within other statements - Ruby - (2011-09-07)
  [3397] Does a for loop evaluate its end condition once, or on every iteration? - (2011-08-18)
  [3254] Multiple inputs, multiple out, ruby functions - (2011-04-19)
  [3253] Is this number between? Does this list include? - Ruby - (2011-04-18)
  [3200] How a for loop works Java, Perl and other languages - (2011-03-12)
  [3158] Ruby training - some fresh examples for string handling applications - (2011-02-05)
  [3156] Splitting data reading code from data processing code - Ruby - (2011-02-04)
  [2975] Why do I need brackets in Ruby ... or Perl, Python, C or Java - (2010-09-29)
  [2892] Alternative loops and conditionals in Ruby and Perl - (2010-07-28)
  [2711] For loop - checked once, or evety time? Ruby v Perl comparison and contrast - (2010-04-07)
  [2619] Passing code to procedures and yield in Ruby - (2010-02-02)
  [2471] A short form of if ... then ... else - (2009-10-23)
  [2287] Learning to program in Ruby - examples of the programming basics - (2009-07-15)
  [1904] Ruby, Perl, Linux, MySQL - some training notes - (2008-11-23)
  [1891] Ruby to access web services - (2008-11-16)
  [1887] Ruby Programming Course - Saturday and Sunday - (2008-11-16)
  [1870] What to do with a huge crop of apples - (2008-11-04)
  [1738] Clean code, jump free (Example in Lua) - (2008-08-06)
  [1696] Saying NOT in Perl, PHP, Python, Lua ... - (2008-07-04)
  [1587] Some Ruby programming examples from our course - (2008-03-21)
  [1582] Ruby, C, Java and more - getting out of loops - (2008-03-19)
  [1220] for loop - how it works (Perl, PHP, Java, C, etc) - (2007-06-06)
  [1163] A better alternative to cutting and pasting code - (2007-04-26)
  [995] Ruby's case - no break - (2006-12-17)
  [985] Equality in Ruby - == eql? and equal? - (2006-12-14)
  [962] Breaking a loop - Ruby and other languages - (2006-12-03)
  [960] 1st, 2nd, 3rd revisited in Ruby - (2006-12-02)

Y105 - Python - Functions, Modules and Packages
  [4212] Python functions - an introduction to how they work - (2013-11-16)
  [4161] Python varables - checking existance, and call by name or by value? - (2013-08-27)
  [4029] Exception, Lambda, Generator, Slice, Dict - examples in one Python program - (2013-03-04)
  [3945] vargs in Python - how to call a method with unknown number of parameters - (2012-12-06)
  [3931] Optional positional and named parameters in Python - (2012-11-23)
  [3885] Default local - a good choice by the author of Python - (2012-10-08)
  [3852] Static variables in Python? - (2012-08-29)
  [3766] Python timing - when to use a list, and when to use a generator - (2012-06-16)
  [3695] Functions are first class variables in Lua and Python - (2012-04-13)
  [3662] Finding all the unique lines in a file, using Python or Perl - (2012-03-20)
  [3474] Python Packages - groupings of modules. An introduction - (2011-10-11)
  [3472] Static variables in functions - and better ways using objects - (2011-10-10)
  [3464] Passing optional and named parameters to python methods - (2011-10-04)
  [3459] Catching the fishes first? - (2011-09-27)
  [3280] Passing parameters to Python functions - the options you have - (2011-05-07)
  [2998] Using an exception to initialise a static variable in a Python function / method - (2010-10-13)
  [2994] Python - some common questions answered in code examples - (2010-10-10)
  [2929] Passing a variable number of parameters in to a function / method - (2010-08-20)
  [2878] Program for reliability and efficiency - do not duplicate, but rather share and re-use - (2010-07-19)
  [2766] Optional and named parameters to Python functions/methods - (2010-05-15)
  [2718] Python - access to variables in the outer scope - (2010-04-12)
  [2520] Global and Enable - two misused words! - (2009-11-30)
  [2506] Good example of recursion in Python - analyse an RSS feed - (2009-11-18)
  [2481] Sample code with errors in it on our web site - (2009-10-29)
  [2440] Optional parameters to Python functions - (2009-10-07)
  [2439] Multiple returns from a function in Python - (2009-10-06)
  [2011] Conversion of OSI grid references to Eastings and Northings - (2009-01-28)
  [1879] Dynamic code - Python - (2008-11-11)
  [1871] Optional and named parameters in Python - (2008-11-05)
  [1869] Anonymous functions (lambdas) and map in Python - (2008-11-04)
  [1790] Sharing variables with functions, but keeping them local too - Python - (2008-09-09)
  [1784] Global - Tcl, PHP, Python - (2008-09-03)
  [1464] Python Script - easy examples of lots of basics - (2007-12-08)
  [1202] Returning multiple values from a function (Perl, PHP, Python) - (2007-05-24)
  [1134] Function / method parameters with * and ** in Python - (2007-04-04)
  [959] It's the 1st, not the 1nd 1rd or 1th. - (2006-12-01)
  [949] Sludge off the mountain, and Python and PHP - (2006-11-27)
  [913] Python - A list of methods - (2006-11-03)
  [912] Recursion in Python - (2006-11-02)
  [900] Python - function v method - (2006-10-20)
  [821] Dynamic functions and names - Python - (2006-08-03)
  [775] Do not duplicate your code - (2006-06-23)
  [749] Cottage industry or production line data handling methods - (2006-06-07)
  [745] Python modules. The distribution, The Cheese Shop and the Vaults of Parnassus. - (2006-06-05)
  [668] Python - block insets help with documentation - (2006-04-04)
  [561] Python's Generator functions - (2006-01-11)
  [418] Difference between import and from in Python - (2005-08-18)
  [386] What is a callback? - (2005-07-22)
  [340] Code and code maintainance efficiency - (2005-06-08)
  [308] Call by name v call by value - (2005-05-11)
  [303] Lambdas in Python - (2005-05-06)
  [294] Python generator functions, lambdas, and iterators - (2005-04-28)
  [105] Distance Learning - (2004-10-31)
  [96] Variable Scope - (2004-10-22)


Back to
Ruby training - some fresh examples for string handling applications
Previous and next
or
Horse's mouth home
Forward to
Extra courses - Advanced PHP, MySQL and Lua
Some other Articles
Keep your business customer-friendly!
TransWilts rail - what picture represents us
Extra courses - Advanced PHP, MySQL and Lua
Returning multiple values from a function call in various languages - a comparison
A new monopoly on the ferry to Northern Ireland
Rake - a build system using code written in Ruby
Changing a class later on - Ruby
4291 posts, page by page
Link to page ... 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86 at 50 posts per page


This is a page archived from The Horse's Mouth at http://www.wellho.net/horse/ - the diary and writings of Graham Ellis. Every attempt was made to provide current information at the time the page was written, but things do move forward in our business - new software releases, price changes, new techniques. Please check back via our main site for current courses, prices, versions, etc - any mention of a price in "The Horse's Mouth" cannot be taken as an offer to supply at that price.

Link to Ezine home page (for reading).
Link to Blogging home page (to add comments).

You can Add a comment or ranking to this page

© WELL HOUSE CONSULTANTS LTD., 2014: Well House Manor • 48 Spa Road • Melksham, Wiltshire • United Kingdom • SN12 7NY
PH: 01144 1225 708225 • FAX: 01144 1225 899360 • EMAIL: info@wellho.net • WEB: http://www.wellho.net • SKYPE: wellho

PAGE: http://www.wellho.net/mouth/3159_Ret ... rison.html • PAGE BUILT: Thu Sep 18 15:30:25 2014 • BUILD SYSTEM: WomanWithCat