Create a two-dimensional array at runtime: Difference between revisions

With language built-in facilities:

#include <istream>

#include <ostream>

delete[] array;

delete[] array_data;

Using std::vector from the standard library:

#include <istream>

#include <ostream>

// the array is automatically freed at the end of main()

=={{header|D}}==

import std.stdio: writef, writefln, readln;

import std.conv: toInt;

writefln("The number at place [0 0] is ", array[0][0]);

}

=={{header|Clean}}==

Start :: *World -> { {Real} }

(_, dim1, console) = freadi console

(_, dim2, console) = freadi console

=={{header|Common Lisp}}==

=={{header|Forth}}==

create ( width height "name" ) over , * cells allot

does> ( x y -- addr ) dup cell+ >r @ * + cells r> + ;

36 0 0 test !

{{libheader|Forth Scientific Library}}

INTEGER DMATRIX my-matrix{{

& my-matrix{{ 8 9 }}malloc

& my-matrix{{ }}free

=={{header|Fortran}}==

In Fortran 90 and later

IMPLICIT NONE

DEALLOCATE (array, STAT=errcheck)

=={{header|Haskell}}==

=={{header|IDL}}==

The following is only for demonstration. No real program should just assume that the user input is valid, integer, large enough etc.

read, y, prompt='Enter y size:'

d = fltarr(x,y)

;==> outputs 5.6

=={{header|J}}==

In J, all aspects of arrays are resolved through evaluation. Everything counts as being given at run time.

'init new' =. 0;1 NB. values for initialization and alteration

array =. y $ init NB. create array of shape y

array =. new element } array NB. amend that element to new value

element { array NB. return value of changed element

Passing two integers to <tt>task</tt> (as a list) satisfies the specifications for a two-dimensional array, but providing a longer list of integers accomplishes the same task on an array of as many dimensions as the count of integers given.

The type of the array is determined by the type of the values used in filling the array. E.g., alternate data types are obtained by substituting any of the following lines:

'init new' =. 1r2;2r3 NB. fractions

=={{header|Java}}==

public class twoDimArray {

System.out.println("The number at place [0 0] is " + array[0][0]);

}

=={{header|Logo}}==

{{works with|UCB Logo}}

mdsetitem [1 1] :a2 0 ; by default, arrays are indexed starting at 1

=={{header|MAXScript}}==

=={{header|OCaml}}==

let nbr2 = read_int ();;

let array = Array.make_matrix nbr1 nbr2 0.0;;

array.(0).(0) <- 3.5;;

=={{header|Pascal}}==

The following code is standard Extended Pascal (tested with <tt>gpc --extended-pascal</tt>):

type

{ get rid of array }

dispose(data);

Predefining an array (or multi-dimension array) size is unnecessary, Perl dynamically resizes the array to meet the requirements. Of course I'm assuming that the user is entering array size 0 based.

# get array sizes from provided params, but force numeric value

my $x = ($_[0] =~ /^\d+$/) ? shift : 0;

print "\n";

}

=={{header|Pop11}}==

incharitem(charin) -> itemrep;

;;; Read sizes

ar(0,0) =>

;;; Make sure array is unreferenced

Pop11 is garbage collected so there is no need to destroy array. However, the array is live as long as variable ar references it. The last assignment makes sure that we loose all our references to the array turning it into garbage.

=={{header|Ruby}}==

w=gets.to_i

arr = Array.new(gets.to_i){Array.new(w)}

arr[1][3] = 5

=={{header|Tcl}}==

Toka has no direct support for 2D arrays, but they can be created and operated on in a manner similar to normal arrays using the following functions.

cells malloc >r

dup cells >r

[ ( value a b address -- )

array.get array.put

And a short test:

10 2 3 r@ 2D-put-element #! Set element 2,3 to 10

2 3 r@ 2D-get-element #! Get the element at 2,3