Short Programming Example (in Many Languages)

[s243a 0]

I want a thread where I can see how to solve a Varity of programming problems in many languages. The idea is so I can read short examples to become fluid in many languages. Both reinforcing what I know and learning new stuff. The problems should have a short solution and be solvable in many different languages. Web applications are alright but make some reference on how the code is used (e.g. CGI). The poster can provide the problem and as many different solutions as he likes. For example:

Problem 1. Write a function to compute a factorial. Solution

Soln. (problem 1.) (Haskell)

fact 1=1fact 0=1fact x=fact(x-1)

Soln. (problem 1.) (MATLAB)

Function y=fact(x)if (y==1) |(y==0)    y=1else    y=x*fact(x-1)end

[Galahad 0]

As I can't think of any simple problem (I'm at work, and cracking my head with different problems ; I'm taking a break), I'll add a solution to factoriel problem, in Visual Basic. It generaly looks almost the same as the solution in matlab, with slight differences... It will be helpfull to beginners in VB, to see how to change the code in some other language, to VB...

Function Fact(ByVal x As Long) As LongIf x < 1 Then  Fact = 1Else  Fact = x * Fact(x - 1)End IfEnd Function

This is a great idea, and an opportunity for all of us to learn something new...

[s243a 0]

[s243a 0]

I got my lisp interpreter to work and the correct code is:

(defun fact (x)    (if (> x 1)        (fact (- x 1))        1))

In my pervious try I made to mistakes. (x>1) should be (> x 1) because in lisp the function or the operation must appear first in the list followed by the arguments. My second mistake was to type (1) instead of 1. When lisp evaluates a list it assumes the first element of the list is a function or operator. 1 is a number not a function or an operator. I also made one minor mistake in my MATLAB code. In the MATLAB example function should start with a lower case letter not an upper case letter. This is due to the annoyance of word converting things to capitals when you dont want it to.

[Galahad 0]

Long time no see
It's been a while since anyone posted anything here, so I'll just add this simple piece of code, hoping someone will add something new

I recently remembered how to swap two variables without the need for the third variable

Dim v1 As Double, v2 As Doublev1 = 17v2 = 2v1 = v1 + v2v2 = v1 - v2v1 = v1 - v2

This code of course won't swap variables that contain objects or are typed (struct) variables, but can be usefull if you have limited memory resources... Variables of course don't need to be double, they can be integer, long... Any size you need

[bjrn 0]

If you want one problem solved in many languages (besides "Hello world" obviously), you should check out 99 bottles of beer.

It's a website with (at the time I'm writing this) program code/scripts that print the lyrics for "99 bottles" (all the way down to the last one) in 729 variations. Those 729 variations do not mean there are 729 languages, but almost, and that includes some pretty weird languages, like whitespace.

[DeveloperX 0]

your function on PHP.
Is this workable?

<?function Fact(x){ if (x < 1){   Fact == 1;}else{ Fact == x * Fact(x - 1);}}?>

[hulunes 0]

well,i think DeveloperX gave the universal algorithm,which is a easy function recursive arithmetic,which remind me in C++:

template<typename T>T function Fact(T n){T r;if(n==0)r=1;elser=n*function Fact(n-1);return r;}

[beeseven 0]

Here are a couple more languages:

Python

def factorial(n):	 if n is 0 or n is 1:		  return 1	 else:		  return n * factorial(n-1)

Java

public static int factorial(int n) {	 if(n == 0 || n == 1)		  return 1;	 else		  return n * factorial(n-1);}

PHP

function factorial($n) {	 if($n == 0 || $n == 1)		  return 1;	 else		  return $n * factorial($n-1);}

Edit: I'd like to add that although the PHP and the Java look very similar, they are very different languages. You'll notice the "int" in the Java example. It's there because Java likes its variables to stay one type, while PHP doesn't really care. This Java code would not work:

String s = "11";s++;//compile-time error

However, similar code in PHP would work:

$s = "11";$s++;//s is now 12 (an int, not a string)

Edited July 28, 2006 by beeseven (see edit history)

[Lobosque 0]

That is the ruby function:

def factorial(i)	 if i == 1 || i == 0		  return 1	 else		  return i * factorial(i-1)	 endend