Recommended Free Pascal Programmming Practices
Read the first comment of each program.



program RFPPP1;
{FPC produces better code for String := ''; than for SetLength(String, 0);}

uses uriparser;

function foo(const URI: TURI): String;
begin
  SetLength(Result, 0);//Add breakpoint at this line
  if Length(URI.Protocol) > 0 then
    Result := LowerCase(URI.Protocol) + ':';
end;

function bar(const URI: TURI): String;
begin
  Result := '';//Add breakpoint at this line
  if Length(URI.Protocol) > 0 then
    Result := LowerCase(URI.Protocol) + ':';
end;

var
  u:TURI;
begin
  u:=Default(TURI);
  writeln(foo(u)+bar(u));
end.



program RFPPP2;
{FPC produces better code for SetLength(String, SaneLength); than for
String := copy(String, 1, SaneLength);
Maximum value of SaneLength must be smaller or equal to the length of the
String, including zero and negative values.}

procedure foo(var Param:string; const SaneLength:integer);
begin
  Param := copy(Param, 1, SaneLength);//Add breakpoint at this line
end;

procedure bar(var Param:string; const SaneLength:integer);
begin
  SetLength(Param, SaneLength);//Add breakpoint at this line
end;

var
  Parameter:string;
  SLen:integer;
begin
  SLen:=length(paramstr(0));
  Parameter:=paramstr(0);
  foo(Parameter,SLen);
  writeln(Parameter);
  Parameter:=paramstr(0);
  bar(Parameter,SLen);
  writeln(Parameter);

  SLen:=1;
  Parameter:=paramstr(0);
  foo(Parameter,SLen);
  writeln(Parameter);
  Parameter:=paramstr(0);
  bar(Parameter,SLen);
  writeln(Parameter);

  SLen:=0;
  Parameter:=paramstr(0);
  foo(Parameter,SLen);
  writeln(Parameter);
  Parameter:=paramstr(0);
  bar(Parameter,SLen);
  writeln(Parameter);

  SLen:=-1;
  Parameter:=paramstr(0);
  foo(Parameter,SLen);
  writeln(Parameter);
  Parameter:=paramstr(0);
  bar(Parameter,SLen);
  writeln(Parameter);
end.



program RFPPP3;
{FPC produces better code for SetLength(String, SaneValue-1); than for
Delete(Param, SaneValue, MaxInt);
Maximum value of SaneValue must be smaller or equal to the length of the
String and the minimum value of SaneValue must be 1.}

procedure foo(var Param:string; const SaneValue:integer);
begin
  Delete(Param, SaneValue, MaxInt);//Add breakpoint at this line
end;

procedure bar(var Param:string; const SaneValue:integer);
begin
  SetLength(Param, SaneValue-1);//Add breakpoint at this line
end;

var
  Parameter:string;
  SLen:integer;
begin
  SLen:=length(paramstr(0))+1;
  Parameter:=paramstr(0);
  foo(Parameter,SLen);
  writeln(Parameter);
  Parameter:=paramstr(0);
  bar(Parameter,SLen);
  writeln(Parameter);

  SLen:=1;
  Parameter:=paramstr(0);
  foo(Parameter,SLen);
  writeln(Parameter);
  Parameter:=paramstr(0);
  bar(Parameter,SLen);
  writeln(Parameter);

  SLen:=0;
  Parameter:=paramstr(0);
  foo(Parameter,SLen);
  writeln(Parameter);
  Parameter:=paramstr(0);
  bar(Parameter,SLen);
  writeln(Parameter);

  SLen:=-1;
  Parameter:=paramstr(0);
  foo(Parameter,SLen);
  writeln(Parameter);
  Parameter:=paramstr(0);
  bar(Parameter,SLen);
  writeln(Parameter);
end.



program RFPPP4;
{FPC produces better code for SetLength(String, Length(String)-1); than for
Delete(Param, Length(String), 1);}

procedure foo(var Param:string);
begin
  Delete(Param, Length(Param), 1);//Add breakpoint at this line
end;

procedure bar(var Param:string);
begin
  SetLength(Param, Length(Param)-1);//Add breakpoint at this line
end;

var
  Parameter1,Parameter2:string;
  last:boolean;
begin
  Parameter1:=paramstr(0);
  Parameter2:=paramstr(0);
  writeln(Parameter1);
  writeln(Parameter2);
  repeat
    last:=(Parameter1='');
    foo(Parameter1);
    bar(Parameter2);
    writeln(Parameter1);
    writeln(Parameter2);
  until last;
  writeln('=====');
end.