Delphi 特性–for-in 循环

从 Delphi 2007 开始支持使用 for-in 循环对集合中的项进行遍历。如：

for Element in ArrayExpr do Stmt;  
for Element in StringExpr do Stmt;  
for Element in SetExpr do Stmt; 
for Element in CollectionExpr do Stmt;

使用例子如下所示：

var
    character: 'a' .. 'z';
    s: string;
begin
    for character in [Low(character) .. High(character)] do
    begin
        s := s + character;
    end;
    ShowMessage(s);  //abcdefghijklmnopqrstuvwxyz
end;