Delphi:计算字符串在另一个字符串中出现的次数

Question

我正在使用Delphi 2007,并想知道是否有一种简单的方法来计算字符串在另一个字符串中出现的次数.我可以使用任何内置函数？

例子:

• 字符串"How are you？"中出现一次"how"
• "do"在字符串"你好吗？"中出现两次.

Answer 1

function Occurrences(const Substring, Text: string): integer;
var
  offset: integer;
begin
  result := 0;
  offset := PosEx(Substring, Text, 1);
  while offset <> 0 do
  begin
    inc(result);
    offset := PosEx(Substring, Text, offset + length(Substring));
  end;
end;

Answer 2

我见过的最聪明的方法之一:

{ Returns a count of the number of occurences of SubText in Text }
function CountOccurences( const SubText: string;
                          const Text: string): Integer;
begin
  if (SubText = '') OR (Text = '') OR (Pos(SubText, Text) = 0) then
    Result := 0
  else
    Result := (Length(Text) - Length(StringReplace(Text, SubText, '', [rfReplaceAll]))) div  Length(subtext);
end;  { CountOccurences }