Arrays

An Array is an ordered collection of values. It holds numbers, strings, or any value, and its indexing is zero-based.

Declaring and creating

Declare with the Array type and assign a literal in square brackets. Elements are separated by commas:

var numeros: Array;
var nomes: Array;

begin
    numeros := [10, 20, 30, 40, 50];
    nomes := ["Alice", "Bob", "Carlos", "Diana"];
    WriteLn("Arrays criados");
end.

Saída

 Arrays criados 

An empty array is []:

var vazio: Array;

begin
    vazio := [];
    WriteLn("Array vazio pronto");
end.

Saída

 Array vazio pronto 

Accessing by index

Use array[index] to read an element. The first element is at index 0:

var numeros: Array;
var nomes: Array;

begin
    numeros := [10, 20, 30, 40, 50];
    nomes := ["Alice", "Bob", "Carlos", "Diana"];

    WriteLn("Primeiro número: ", numeros[0]);
    WriteLn("Último nome: ", nomes[3]);
end.

Saída

 Primeiro número: 10 Último nome: Diana 

Assigning elements

Modify an element with array[i] := value;:

var numeros: Array;

begin
    numeros := [10, 20, 30];
    numeros[2] := 99;
    WriteLn("Terceiro após modificação: ", numeros[2]);
end.

Saída

 Terceiro após modificação: 99 

Iterating with for..in

The most direct way to traverse an array is for..in, which hands you each element directly:

var numeros: Array;
var item: Integer;
var soma: Integer;

begin
    numeros := [10, 20, 30, 40, 50];
    soma := 0;
    for item in numeros do
    begin
        WriteLn("  ", item);
        soma := soma + item;
    end;
    WriteLn("Soma: ", soma);
end.

Saída

 10 20 30 40 50 Soma: 150 

It also works with string arrays:

var nomes: Array;
var nome: String;

begin
    nomes := ["Alice", "Bob", "Carlos"];
    for nome in nomes do
        WriteLn("Olá, ", nome, "!");
end.

Saída

 Olá, Alice! Olá, Bob! Olá, Carlos! 

Out-of-range indexes

Accessing a nonexistent index throws an error at runtime:

var numeros: Array;

begin
    numeros := [10, 20, 30];
    WriteLn(numeros[5]);   // error: index out of range
end.

Out of range is catchable

An out-of-bounds access raises an error that you can wrap in try/catch. See Error handling.

Helper functions

For more advanced operations — sorting, filtering, mapping, summing, concatenating — import the internal.collections library:

uses internal.collections;

var numeros: Array;

begin
    numeros := [3, 1, 2];
    WriteLn("Tamanho: ", arraySize(numeros));
    WriteLn("Soma: ", arraySum(numeros));
end.

Saída

 Tamanho: 3 Soma: 6 

Full collections

internal.collections provides arraySort, arrayFilter, arrayMap, arrayReduce, arrayReverse, arrayContains, and much more. See Internal libraries.

Next, learn how to handle runtime failures in Error handling.