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Jeroen W. Pluimers on .NET, C#, Delphi, databases, and personal interests

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Archive for June 17th, 2020

Chr equivalent for Unicode in Delphi 7 – Stack Overflow

Posted by jpluimers on 2020/06/17

From a long time ago: [WayBackchr equivalent for Unicode in Delphi 7 – Stack Overflow answered by David Heffernan:

Q

I need to initialize a Widestring in Delphi 7 but I can’t use chrfunction which is ANSI

var
  ws : Widestring;
begin

 ws := chr($FFFF) + chr($FFFF) + chr($FFFF);

end;

What can I use, then ?

A

I’m not sure there’s a simply way to do what you wish. You can convert a Word into a WideChar with a simple cast:

WideChar($FFFF)

but you cannot concatenate WideChar. So this is a compiler error:

WideChar($FFFF) + WideChar($FFFF)

You could use a helper function to get the job done:

function InitialiseWideString(const chars: array of Word): WideString;
var
  i: Integer;
begin
  SetLength(Result, Length(chars));
  for i := 0 to high(chars) do
    Result[i+1] := WideChar(chars[i]);
end;

Then you can call it like this:

ws := InitialiseWideString([$0054, $0069, $006D, $0065, $0020, $0074, $006F, 
  $0020, $0075, $0070, $0067, $0072, $0061, $0064, $0065]);

–jeroen

Posted in Delphi, Delphi 7, Development, History, Software Development | 3 Comments »

Dynamically instantiating instances in Delphi without knowing their full type is hard

Posted by jpluimers on 2020/06/17

For my reading list: [WayBack] So am working on a particular .NET project and came across NewtonSoft JSON.NET Serializer, it allows you serialize Collections such as a generic list an… – Ugochukwu Mmaduekwe – Google+:

Stefan Glienke:
Serializing and mostly deserializing generics in Delphi is a major PITA because we don’t have such capabilities to dynamically work with them like in C# where you can easily create new generic lists at runtime where you don’t know the precise type T at compile time.

–jeroen

 

Posted in .NET, C#, Delphi, Development, Software Development | Leave a Comment »

How to return a string value from a Bash function – Stack Overflow

Posted by jpluimers on 2020/06/17

Cool: you can return strings both as a function result, and by reference: they are explained in the question, second and fourth answer of [WayBack] How to return a string value from a Bash function – Stack Overflow.

Returning them by reference has two important benefits:

  1. it is much faster (especially useful in tight loop)
  2. you can use echo (normally used to return a result) for debugging purposes

I also needed a bit of switch magic which I found at [WayBack] bash – Switch case with fallthrough? – Stack Overflow and array magic (from [WayBack] Array variables) as arrays are far more readable than indirection (on the why not, see [WayBack] BashFAQ/006 – Greg’s Wiki: How can I use variable variables (indirect variables, pointers, references) or associative arrays?).

So here is a function that returns a specific IPv4 octet.

function getIpv4Octet() {
  IPv4=$1
  octetIndex=$2
  outputVariable=$3

  slice="${IPv4}"
  count=1
  while [ "${count}" -le 4 ]
  do
    octet[${count}]="${slice%%.*}"
    slice="${slice#*.}"
    count=$((count+1))
  done
   
  case "${octetIndex}" in
    "1" | "2" | "3" | "4")
      ;;
    *)
      octetIndex="4"
      ;;
  esac
  eval $outputVariable="${octet[$octetIndex]}"
}

You call it like this:

$ getIpv4Octet "192.168.178.32" 3 result && echo ${result}
178

–jeroen

Posted in *nix, *nix-tools, bash, bash, Development, Power User, Scripting, Software Development | Leave a Comment »

 
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