Delphi的StringReplace 字符串替换函数

function StringReplace (const S, OldPattern, NewPattern: string;Flags: TReplaceFlags): string;

rfReplaceAll：全部替换
rfIgnoreCase：忽略大小写

For Example：

var
    aStr:String;
begin
    aStr :='This is a book, not a pen!';
   ShowMessage(StringReplace (aStr, 'a', 'two', []));//This is twobook, not a pen!只替换了第一个符合的字
   ShowMessage(StringReplace (aStr, 'a', 'two',[rfReplaceAll]));//This is two book, not two pen!替换了所有符合的字
    aStr :='This is a book, not A pen!';
   ShowMessage(StringReplace (aStr, 'a', 'two',[rfReplaceAll]));//This is two book, not A pen!只替换了符合的字(小写a)
   ShowMessage(StringReplace (aStr, 'a', 'two', [rfReplaceAll,rfIgnoreCase]));//This is two book, not twopen!不管大小写替换了所有符合的字
end;