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Array concatenation: Difference between revisions
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=={{header|Delphi}}==
2022/07/13
<lang delphi>
// This example works on stuff as old as Delphi 5 (maybe older)
// Modern Delphi / Object Pascal has both
// • variant types
// • the ability to concatenate arrays with the '+' operator
// So I could just say:
// myarray := [1] + [2, 3];
// But if you do not have access to the latest/greatest, then:
{$apptype console}
type
// Array types must be declared in order to return them from functions
// They can also be used with open array parameters.
TArrayOfString = array of string;
function Concat( a, b : array of string ): TArrayOfString; overload;
{
Every array type needs its own 'Concat' function:
function Concat( a, b : array of integer ): TArrayOfInteger; overload;
function Concat( a, b : array of double ): TArrayOfDouble; overload;
etc
Also, dynamic and open array types ALWAYS start at 0. No need to complicate indexing here.
}
var
n : Integer;
begin
SetLength( result, Length(a)+Length(b) );
for n := 0 to High(a) do result[ n] := a[n];
for n := 0 to High(b) do result[Length(a)+n] := b[n]
end;
// Example time!
function Join( a : array of string; sep : string = ' ' ): string;
var
n : integer;
begin
if Length(a) > 0 then result := a[0];
for n := 1 to High(a) do result := result + sep + a[n]
end;
var
names : TArrayOfString;
begin
// Here we use the open array parameter constructor as a convenience
names := Concat( ['Korra', 'Asami'], ['Bolin', 'Mako'] );
WriteLn( Join(names) );
// Also convenient: open array parameters are assignment-compatible with our array type!
names := Concat( names, ['Varrick', 'Zhu Li'] );
WriteLn( #13#10, Join(names, ', ') );
names := Concat( ['Tenzin'], names );
Writeln( #13#10, Join(names, #13#10 ) );
end.
</lang>
Output:
Korra Asami Bolin Mako
Korra, Asami, Bolin, Mako, Varrick, Zhu Li
Tenzin
Korra
Asami
Bolin
Mako
Varrick
Zhu Li
<br>
What follows is older content found on this page.<br>
It has running commentary about memory management that isn’t exactly correct.<br>
Delphi handles dynamic array memory very well.
<lang delphi>type
TReturnArray = array of integer; //you need to define a type to be able to return it
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