[SOLVED] how to pass dynamic array by value?

[nds]

Code: Pascal  [Select][+][-]

1. Procedure arrp(var a: array of string);
2. Begin
3. Setlength(a,1);
4. End;

Type mismatch on Lazarus 2.2.2

[MarkMLl]

Don't just post a fragment, post a complete compilable example.

Try defining a type for a prior to the procedure declaration.

MarkMLl

[nds]

Don't just post a fragment, post a complete compilable example.

Code: Pascal  [Select][+][-]

1. program Project1;
2. procedure arrp(var a: array of string);
3. begin
4.  setlength(a,1);
5.  end;
6. var a:array of string;
7. begin
8.   arrp(a);
9. end.  
10.  

Try defining a type for a prior to the procedure declaration.

dynamic array - built-in type

[MarkMLl]

dynamic array - built-in type

"Array of string" is not a built-in type.

MarkMLl

[nds]

https://wiki.freepascal.org/Dynamic_array

this code works

Code: Pascal  [Select][+][-]

1. program Project1;
2. var a:array of string;
3. begin
4.    setlength(a,1);
5. end.
6.  

[Warfley]

This is not an dynamic array but an open array. The syntax for both is the same, but they are different concepts.

To use a dynamic array as function parameter you need to define the type as an explicitly named type:

Code: Pascal  [Select][+][-]

1. type TDynStringArray = array of String;
2. procedure Foo(arr: TDynStringArray);
3. ...

Some types are already pre-defined for example the generic TArray:

Code: Pascal  [Select][+][-]

1. procedure Foo(arr: specialize TArray<String>);
2. ...

[marcov]

Code: Pascal  [Select][+][-]

1. Procedure arrp(var a: array of string);
2. Begin
3. Setlength(a,1);
4. End;

Type mismatch on Lazarus 2.2.2

You try to pass a dynamic array to an open array parameter. Despite having roughly the same syntax, they are not the same. To do what you want, define array of <x> as a separate type, or better use the predefined ones for basic types in types uni like https://www.freepascal.org/docs-html/rtl/types/tstringdynarray.html

[nds]

Warfley, marcov Thanks