Data registration in a dynamic array returning Eaccesviolation

Question

I’m trying to create a Delphi database to register and save to a 3 basic variables dynamic array. To do this, I created a global dynamic array named Pedidos, one Record Tpedidoitem with id, name and value, and other Record Ordered that receives the record Tpedidoitem:

TPedidoItem= record
id: Integer;
nome: string;
valor: Real;
end;
TPedido= record
pedido: TPedidoItem
end;

How I declared the dynamic array:

private
Pedidos: array of TPedidoItem;

After that, I call a registration process that saves instances of values, adds one more space in the array Pedidos,saves this data in the array and then displays the values in a label screen:

procedure TForm1.CadastrarClick(Sender: TObject);
var
pedido: TPedidoItem;
tamanho: Integer;
begin
    tamanho:= Length(Pedidos)+ 1;
    SetLength(Pedidos,tamanho);

    with pedido do
    begin
        id:= StrToInt(Ed3Num1.Text);
        nome:= Ed3Text1.Text;
        valor:= StrToInt(Ed3Num2.Text);
    end;

    Pedidos[tamanho].id:= pedido.id;
    Pedidos[tamanho].nome:= pedido.nome;
    Pedidos[tamanho].valor:= pedido.valor;

    Lista3.Caption:=Lista3.Caption +'Id: '+ IntToStr(Pedidos[tamanho].id)
        + ' | Nome: '+ Pedidos[tamanho].nome
        + ' | Valor: ' + FloatToStr(Pedidos[tamanho].valor)+#13;

end;

I tried to debug to see what I was doing wrong, however, the program performs all the tasks until the end without showing the error, the error only appears after having reached the end; process. You know what I’m doing wrong? Something tells me it might be the way I’m trying to save the data in the dynamic array, but I don’t know how I should save it.

Progress(more or less)

I discovered the problem, the program tried to save the data in a position of the array that did not exist. I managed to solve the problem in a completely inefficient way:

tamanho:= tamanho - 1;
Pedidos[tamanho].id:= pedido.id;
Pedidos[tamanho].nome:= pedido.nome;
Pedidos[tamanho].valor:= pedido.valor;

Lista3.Caption:=Lista3.Caption +'Id: '+ IntToStr(Pedidos[tamanho].id)
    + ' | Nome: '+ Pedidos[tamanho].nome
tamanho:= tamanho + 1;

Considering the above code, what would be the best way to register the data with this dynamic array

Answer 1

Change the approach, where this using:

tamanho:= Length(Pedidos)+ 1;
SetLength(Pedidos,tamanho);

with pedido do
begin
    id:= StrToInt(Ed3Num1.Text);
    nome:= Ed3Text1.Text;
    valor:= StrToInt(Ed3Num2.Text);
end;

Try something like:

SetLength(Pedidos, Succ(Length(Pedidos)));
vIdx := High(Pedidos);
Pedidos[vIdx].id:= StrToInt(Ed3Num1.Text);
Pedidos[vIdx].nome:= Ed3Text1.Text;
Pedidos[vIdx].valor:= StrToInt(Ed3Num2.Text);

In this model you don’t need the variable pedido