Strings and Runes in Modelica

In Modelica, strings are represented as arrays of characters. Unlike Go, Modelica doesn’t have a built-in concept of runes or Unicode code points. However, we can still demonstrate some string operations and character handling.

model StringsAndCharacters
  constant String s = "Hej!"; // "Hello" in Swedish

  function printCharacters
    input String str;
  algorithm
    for i in 1:Modelica.Strings.length(str) loop
      Modelica.Utilities.Streams.print(String(Modelica.Strings.getChar(str, i)));
    end for;
  end printCharacters;

  function examineCharacter
    input Integer c;
  algorithm
    if c == 72 then // ASCII code for 'H'
      Modelica.Utilities.Streams.print("Found H");
    elseif c == 101 then // ASCII code for 'e'
      Modelica.Utilities.Streams.print("Found e");
    end if;
  end examineCharacter;

algorithm
  // Print the length of the string
  Modelica.Utilities.Streams.print("Len: " + String(Modelica.Strings.length(s)));

  // Print each character in the string
  Modelica.Utilities.Streams.print("Characters:");
  printCharacters(s);

  // Examine each character
  for i in 1:Modelica.Strings.length(s) loop
    examineCharacter(Integer(Modelica.Strings.getChar(s, i)));
  end for;
end StringsAndCharacters;

In this Modelica example:

1. We define a constant string s with the value “Hej!” (which means “Hello” in Swedish).

2. The printCharacters function demonstrates how to iterate over each character in a string.

3. The examineCharacter function shows how we can check for specific characters. In Modelica, we use the ASCII integer value of characters for comparison.

4. In the main algorithm section:

   • We print the length of the string using Modelica.Strings.length().
   • We print each character in the string using our printCharacters function.
   • We examine each character using our examineCharacter function.

Note that Modelica doesn’t have built-in support for Unicode or multi-byte character encodings like UTF-8. It primarily works with ASCII characters. For more complex string operations or Unicode support, you might need to use external C functions or libraries.

To run this Modelica model, you would typically use a Modelica simulation environment like OpenModelica or Dymola. The exact output would depend on the simulation environment, but it would show the length of the string, print each character, and indicate when it finds the characters ‘H’ and ’e’.