Difference between revisions of "Recital Arrays"

Revision as of 10:54, 26 July 2010

Recital Arrays

An Overview of Arrays in Recital

How to Create a Static Array in Recital

Static Arrays

A static array is an ordered list of elements (variables) that is of a fixed size (number of elements). You declare a static array by specifying the number of elements when you declare a variable.

private tab[ 20 ]    // declare a static array of 20 elements all initialized to False
 
// iterate through the array (note the use of the alen( ) function to find the length of the array
for i=1 to alen( tab )
    // change each array element to hold a numeric value
    tab[ i ] = i
endfor

You can initialize a static array with one statement.

// declare the array and init all elements to false
declare tab[10, 10]
 
// init all elements to zero
tab = 0

You can create and initialize static arrays using static array initializers.

// simple one dimensional array with 2 elements
private tab = { "Hello", "world" }
 
// two-dimensional array of two rows with three columns in each row
private tab2 = { { "Hello", 10, date() ], { "world", 20, date()+1 } }
 
// create an array on the fly
mytab = { 10, 20, 30, 40, 50, 60 }

You can view the contents of a static array using the echo or ? commands.

? tab

How to Create an Associative Array in Recital

An associative array (also known as a dynamic array) is a collection of key/value pairs where the key can be used to retrieve the value. Associative arrays are dynamic, meaning that elements can be added and removed dynamically.

private tab[]    // note the use of [] to denote a dynamic array
 
tab["name"] = "bill"
tab["age"] = 25
tab["dob"] = date()

Associative arrays can be created and initialized in one statement using the array( ) function.

tab = array("name" => "bill", "age" => 25, ""dob" => date())

You can view the contents of an associative array using the echo or ? commands.

? tab

Accessing Elements in a Static Array

• aelement() - return the number of an array element from the element subscripts

number = aelement(arrayname as character, row as numeric [, column as numeric])

• asubscript() - return the row or column subscript of an array element from the element number

number = asubscript(arrayname as character, element as number, roworcolumn as numeric)

• alen() - return the number of elements, rows or columns of an array

number = alen(arrayname as character [, rowsorcolumns as numeric)

Accessing Elements in an Associative Array

Changing, Adding and Removing Elements From Arrays

• aadd() - add a new element to the end of an array

expression = aadd(arrayname as character, newelement as expression)

• adel() - delete an element from an array

logical = adel(arrayname as character, element as numeric | row as numeric [, dimension as numeric])

• asize() - resize an array

asize(arrayname as character, elements as numeric)

Looping Through Arrays

The foreach...endfor command is used to iterate over each element in an array or member in an object or associative array.

foreach <array> as <value as variable> | <array> as <key variable> => <value as variable>
<statements>
endfor

The array must be the name of an existing array or object. The value is a reference to be loaded with the contents of each element or member in turn. Using the <key> => <value> syntax, the member names of an object or associative array can also be accessed.

Examples

// static array
numbers = array(1,2,3,4,5,6,7,8,9,10)
foreach numbers as elem
    ? elem * elem
endfor
 
// associative array
private myarray = array("Name" => "Recital", "Description" => "database")
foreach myarray as key => value
    echo "key=" + key + " value=" + value + "\n"
endfor

Replacing Sections of an Array

• acopy() - copy elements from one array to another

logical = acopy(fromarrayname as character, toarrayname as character [, fromstartelement as numeric 
  [, elements as numeric [, tostartelement as numeric]]])

Sorting an Array

• asort() - sort the character elements of the specified array

logical = asort(arrayname as character [, startelement as numeric [, endelement as numeric [, reverse as numeric]]])

Passing Arrays as Function Arguments

Miscellaneous Array Functions

Table and File Information in Arrays

• abrowse() -
• acol() - return a column coordinate from an array in abrowse()
• arow() - return a row coordinate from an array in abrowse()
• adir() -
• afields() -

Converting a String Into an Array

• astore() - fill an array from a string with separate character elements and return the number of elements

numeric = astore(arrayname, string as character, separator as character)

• explode() - separate a character string into individual elements and return as an array

array = explode(separator as chatacter, string as character)

Converting an Array into a String

• astring() - return an array as a character string, with the elements separated by a comma or other specified character

character = astring(arrayname [, separator as character])

• implode() - return an array as a character string, with the elements separated by a specified character

character = implode(separator as character, arrayname)

Numeric Array Functions

• aaverage() - calculate the average of element values in an array

numeric = aaverage(arrayname as character)

• amax() - return the highest element value in an array

numeric = amax(arrayname as character)

• amin() - return the lowest element value in an array

numeric = amin(arrayname as character)

• asum() - calculate the sum of element values in an array

numeric = asum(arrayname as character)

Summary