I am converting code from Lazarus to Delphi 10.4 Sydney and have a line that throws an error:

// Split line and put it into a new array, txtDataArray
txtDataArray := txtToParse.Split(['.', ',', '!'], TStringSplitOptions.ExcludeEmpty);

txtToParse is comma delimited text variable.

How would I correctly write that to work in Delphi 10.4 Sydney?

I tried this and I get an error that states:

Incompatible Types - a Dynamic Array and System TArray<System String> at line 340:

Under var I have:

// For splitting
charArray : Array[0..2] of Char;
txtToParse : String;
txtArray : array of String;

Then in the main function I have:

// Split line and put it into a new array, txtArray
charArray[0] := '.';
charArray[1] := ',';
charArray[2] := '!';
txtArray := txtToParse.Split(charArray);

How can I get this to work in Delphi 10.4 Sydney?

CodePudding user response：

You need to change this declaration:

txtArray : array of String;

To this:

txtArray : TArray<String>;

The reason is explained in detail in the documentation:

Type Compatibility and Identity (Delphi)

And in particular:

Array Types and Assignments

Arrays are assignment-compatible only if they are of the same type. Because the Delphi language uses name-equivalence for types, the following code will not compile.

var
  Int1: array[1..10] of Integer;
  Int2: array[1..10] of Integer;
...
Int1 := Int2; 

To make the assignment work, declare the variables as:

var
  Int1, Int2: array[1..10] of Integer; 

or:

type
  IntArray = array[1..10] of Integer;
var
  Int1: IntArray; Int2: IntArray;

And

Overloads and Type Compatibility in Generics

Two non-instantiated generics are considered assignment compatible only if they are identical or are aliases to a common type.

Two instantiated generics are considered assignment compatible if the base types are identical (or are aliases to a common type) and the type arguments are identical.

In FreePascal, Split() returns a TStringArray which is a plain vanilla alias for array of string, and so is assignment-compatible with an array of string variable.

But in Delphi, Split() returns a TArray<String>, which is a Generic alias for array of T where T is string, so it is a distinct Generic type, and thus is not assignment-compatible with an array of String variable, only with a TArray<String> variable.