1. Pascal / Говнокод #15801

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    {*********** PosEx ***********}
function Posex(const substr,str:string; const startloc:integer):integer;
{Search for "substr" in "str" starting at "startloc" return 0 or the start
 postion where "substr" was found}
var
  i, j,k,ssLen, sLen, stop:integer;
  a:char;
begin
  result:=0;
  ssLen:=length(substr);
  slen:=length(str);
  stop:=slen-sslen+1; {highest feasible start location for substring}
  if (ssLen=0) or (sslen>sLen) then exit;
  a:=substr[1];  {1st letter of substr}
  i:=startloc; {start search location}
  while (i<=stop) and (result=0) do
  begin
    while (i<=stop) and (a<>str[i]) do inc(i); {find the 1st letter}
    if i<=stop then
    begin
      if sslen=1 then  result:=i {It was a 1 character search, so we're done}
      else
      begin
        j:=2;
        k:=i-1; {back "K" up by 1 so that we can use K+j as the index to the string}
        while (j<=sslen) do
        begin {compare the rest of the substring}
          if (substr[j]<>str[k+j]) then break
          else inc(j); {The letter matched, go to the next+
                   {When we pass the substring end, "while" loop will terminate}
        end;
        if (j>sslen) then
        begin
          result:=i;
          exit;
        end
        else inc(i); {that search failed, look for the next 1st letter match}
      end;
    end;
  end;
end;

    Несколько вложенных циклов - это НЕ может работать быстро.
    Для сравнения - функция PosEx из StrUtils.pas

    function PosEx(const SubStr, S: string; Offset: Cardinal = 1): Integer;
    
var
    
  I,X: Integer;
    
  Len, LenSubStr: Integer;
    
begin
    
  if Offset = 1 then
    
    Result := Pos(SubStr, S)
    
  else
    
  begin
    
    I := Offset;
    
    LenSubStr := Length(SubStr);
    
    Len := Length(S) - LenSubStr + 1;
    
    while I <= Len do
    
    begin
    
      if S[i] = SubStr[1] then
    
      begin
    
        X := 1;
    
        while (X < LenSubStr) and (S[I + X] = SubStr[X + 1]) do
    
          Inc(X);
    
        if (X = LenSubStr) then
    
        begin
    
          Result := I;
    
          exit;
    
        end;
    
      end;
    
      Inc(I);
    
    end;
    
    Result := 0;
    
  end;
    
end;


    А вот что пишет автор:
    The Delphi "Pos" function searches for a
    
substring within a string.  Later versions of
    
Delphi also include a "PosEx" function 
    
which
    
starts the search at a given position so 
    
multiple calls can return all occurrences.
    

    
This program tests DFF versions of these 
    
two
    
functions. Pos was rewritten to provide a 
    
base
    
of code for PosEx.  And PosEx wll provide 
    
the
    
missing function for versions of Delphi 
    
before
    
Delphi 7.
    

    
As an unexpected bonus, it appears that the
    
DFF versions of Pos and Posex are slightly
    
quicker than the D7 versions.

    Запостил: brutushafens, 20 Апреля 2014

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