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==[[Python]]== |
==[[Python]]== |
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[[Category:Python]] |
[[Category:Python]] |
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<pre> |
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values = range(10) |
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evens = [x for x in values if not(x & 1)] |
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ievens = (x for x in values if not(x & 1)) # lazy |
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</pre> |
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==[[Ruby]]== |
==[[Ruby]]== |
Revision as of 14:40, 25 January 2007
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You are encouraged to solve this task according to the task description, using any language you may know.
You are encouraged to solve this task according to the task description, using any language you may know.
Select certain elements from an Array into a new Array in a generic way. E.g., select all even numbers from an Array
AppleScript
set array to {1, 2, 3, 4, 5} set evens to {} repeat with i in array -- very important -- list index starts at 1 not 0 if (i mod 2 = 0) then set evens to evens & i end repeat
C
int arr[5] = {1,2,3,4,5}; int *result; int memoryReqd = 0,length = sizeof(arr)/sizeof(arr[0]), i,j; for (i=0; i<length; i++) { if(0 == arr[i]%2) { memoryReqd++; } } result = (int*)malloc(memoryReqd*sizeof(int)); for(i=0,j=0; i<length; i++) { if(0 == arr[i]%2) { result[j++]=arr[i]; } }
// Test our resultant array for(i=0; i<memoryReqd; i++) { printf("%d\n",result[i]); }
C++
Using STL and Boost.Lambda with Microsoft Visual C++ 2005
using namespace std; using namespace boost::lambda; vector<int> ary(10); int i = 0; for_each(ary.begin(), ary.end(), _1 = ++var(i)); // init array vector<int> evens; remove_copy_if(ary.begin(), ary.end(), back_inserter(evens), _1 % 2); // filter copy
C#
// .NET 1.x solution ArrayList array = new ArrayList( new int[] { 1, 2, 3, 4, 5 } ); ArrayList evens = new ArrayList(); foreach( int i in array ) { if( (i%2) == 0 ) evens.Add( i ); } foreach( int i in evens ) System.Console.WriteLine( i.ToString() );
// .NET 2.0 solution List<int> array = new List<int>( new int[] { 1, 2, 3, 4, 5 } ); List<int> evens = array.FindAll( delegate( int i ) { return (i%2)==0; } ); foreach( int i in evens ) System.Console.WriteLine( i.ToString() );
Haskell
ary = [1..10] evens = [ x | x <- ary, even x ]
Java
int[] array = new int[] {1, 2, 3, 4, 5 }; List<Integer> evensList = new ArrayList<Integer>(); for (int i: array) { if (i % 2 == 0) evensList.add(i); } int[] evens = evensList.toArray(new int[0]);
JavaScript
var arr = [1,2,3,4,5]; var evens = []; for (var i=0, ilen=arr.length; i<ilen; i++) if (arr[i] % 2 == 0) evens.push(arr[i]);
Perl
my @list = (1, 2, 3, 4, 5, 6); my @even = grep { 0 == $_%2; } @list;
PHP
//using a standard loop $arr = range(1,5); $evens = array(); foreach ($arr as $val) if ($val % 2 == 0) array_push($evens,$val); print_r($evens);
//using a filter function function is_even($var) { return(!($var & 1)); } $arr = range(1,5); $evens = array_filter($arr, "is_even"); print_r($evens);
Python
values = range(10) evens = [x for x in values if not(x & 1)] ievens = (x for x in values if not(x & 1)) # lazy
Ruby
ary = [1,2,3,4,5,6] #or ary = (1..6).to_a even_ary = ary.select{|el|el%2==0} # => [2, 4, 6]
Standard ML
val ary = [1,2,3,4,5,6]; List.filter (fn x => x mod 2 = 0) ary