Trouble converting delphi procedure to C#

Question

I've been at this for a bit with no luck.

I have this delphi procedure which I did not write and don't have the original program to test. Please take note of the comment to see what it's supposed to do:

// first parameter is an input string, and the others are returned contents
// parsed. Example: "Okay:C15" would be parsed as "Okay", "C", 15, 0
procedure TestingThis(const astring: string; var aname: string;
                     var atype: char; var alength: byte; var adecimals: byte);
var
  ipos,jpos: integer;
  aa: string;
begin
  aname:='';
  atype:='C';
  alength:=1;
  adecimals:=0;
  aa:=astring;
  ipos:=pos(':',aa);
  if ipos > 1 then
  begin
     aname:=copy(aa,1,ipos-1);
     aa:=copy(aa,ipos+1,length(aa)-ipos);
     atype:=aa[1];
     if atype = 'A' then exit;
     if atype = 'B' then
     begin
       alength:=8;
       exit;
     end;
     if atype = 'C' then
     begin
        alength:=strtoint(copy(aa,2,length(aa)-1));
        exit;
     end;
     if atype = 'D' then
     begin
       jpos:=pos('.',aa);  
       if jpos < 1 then  
       begin
         alength:=strtoint(copy(aa,2,length(aa)-1));
         adecimals:=0;
       end
       else
       begin
         alength:=strtoint(copy(aa,2,jpos-2));
         adecimals:=strtoint(copy(aa,jpos+1,length(aa)-jpos));
       end;
       exit;
     end;
  end;
end;

Here's my C# version:

public static void TestingThis(string astring)
        {
            int ipos;
            int jpos;
            string aa;
            string aname = "";
            char atype = 'C';
            // def
            byte alength = 1;
            byte adecimals = 0;
            aa = astring;
            ipos = aa.IndexOf(':'); 

            if (ipos > 0)
            {
                aname = aa.Substring(0,ipos); 
                aa = aa.Substring(ipos + 1, aa.Length - ipos - 1); 
                atype = aa[0]; 

                if (atype == 'L')
                {
                    return; 
                }
                if (atype == 'D')
                {
                    alength = 8;
                }
                if (atype == 'C')
                {
                    if (Byte.TryParse(aa.Substring(1, aa.Length - 1), out alength)) //Get the last two elements of string and convert to type byte
                    {
                        return;
                    }
                }
                if (atype == 'N')
                {
                    jpos = aa.IndexOf('.'); 

                    if (jpos < 0) // if '.' isn't found in string
                    {
                        if (byte.TryParse(aa.Substring(1, aa.Length - 1), out alength))
                        {
                            adecimals = 0;
                            return; 
                        }
                    }
                    else
                    {
                        if ((byte.TryParse(aa.Substring(2, jpos - 2), out alength)) && (byte.TryParse(aa.Substring(jpos + 1 ,aa.Length - jpos), out adecimals)))
                        {
                            return;
                        }
                    }
                    return;
                }
            }    
        }

I've tested it by giving it a string like:

string test = "Okay:C15"
TestingThis(test)

I'm confused though. In the Delphi code, only one parameter is an input: astring, and the rest are supposedly returned values? How is this possible? I haven't seen anything about one parameter going in and 4 going out From what I read, the var keyword means they are passed by reference, which means I should use ref in the c# version. The function itself is supposedly only called once, and the input is in fact a single string.

Edit: Changed my function to this:

public static void TestingThis(string astring, out string aname, out char atype, out byte alength, out byte adecimals)

And I call it like this:

    string test = "Okay:C15";
    string aname;
    char atype;
    byte alength;
    byte adecimals;
    TestingThis(test, out aname, out atype, out alength, out adecimals);

Is this correct conversion from Delphi to C#?

`var` is a key word in C# that `implicitly vs explicitly` tells you what the variable type is .. also you can return as many values from a method if the method signature has the `out` parameter for example `var myVar = new DataTable` this is the same as saying explicitly `DataTable myVar = new DataTable()` and to pass by ref in C# you would still need to have the `ref` key word declared in the method signature as well do a google search on `C# MSDN var` also if you are expecting to return a value from your C# method that you posted then you need to change the void to an actual datatype — MethodMan, Feb 19 '16 at 17:24
The `var` is in the delphi part, which I was going to switch to `ref` in C# as I read that was its counterpart. So for all parameters listed as `var` in delphi, which are supposed to be the returned parameters, would the C# equivalent be `out ref paramName` ? Edit: N/m doesn't work like that. Hmm. — pfinferno, Feb 19 '16 at 17:33
it would just be `out` take a look at this excellent post / explanation - http://stackoverflow.com/questions/1516876/when-to-use-ref-vs-out I also know Delphi exceptionally well coded it for 17 out of my 22 yrs of coding — MethodMan, Feb 19 '16 at 17:36
Hmm, so in Delphi you don't have to initialize the parameters and put them in the call to get values for them? For instance, I don't see any of the other parameters anywhere, just the input string for the function. I'm not able to do this in C# though, it looks like I have to initialize and put them as parameters first. — pfinferno, Feb 19 '16 at 17:41
that's correct delphi you don't have to initialize parameters but C# .net you do especially the ones that you will use as out parameters.. — MethodMan, Feb 19 '16 at 17:45
Thank you. Last question, your first post said to use ref to pass by `ref` in C#, but say just to use `out` in your next one. Which is correct? I'm going to edit my main post with what I have now. — pfinferno, Feb 19 '16 at 17:49
if you are wanting to return multiple values in a method that are not by ref for example if you call a method and want to return someone's age.. why would you change the age to the return values age by using the ref key word when all you need to do is use a simple out param.. do a msdn google search on C# out parameters you need to understand the clear difference between ref.. and out.. also if you want to use as a global variable for example you would pass those ref values in your method. but windows and web are different .. so beware when you start coding more frequently in both. — MethodMan, Feb 19 '16 at 17:53
Okay, I think I understand now. Could you please take a look at my last edit? — pfinferno, Feb 19 '16 at 17:56
you still need to initialize the out parameters either do the following for example ` string aname = string.Empty;` or you could use the (default) key word but I prefer string.Empty vs `string aname = (default)string;` always initialize integers = 0, objects = null, string=string.Empty; or some string value. char = `' '` decimals = 0.0 not 0 etc.. you get the drift — MethodMan, Feb 19 '16 at 18:00

score 1 · Accepted Answer · answered Feb 19 '16 at 18:53

If you are wanting to return multiple values in a method that are not by ref for example if you call a method and want to return someone's age.. why would you change the age to the return values age by using the ref key word when all you need to do is use a simple out param.. do a msdn google search on C# out parameters you need to understand the clear difference between ref.. and out.. also if you want to use as a global variable for example you would pass those ref values in your method. but windows and web are different .. so beware when you start coding more frequently in both

Trouble converting delphi procedure to C#

1 Answers1