..............46 第五章 代码块和迭代器.................................................................................................................48 §5.1 代码块(Block) ...............................................................................................................48 §5.1.1 什么是代码块.......................................................................................................48 §5.1.2 代码块与对象.......................................................................................................48 §5.2 迭代器(Iterator) .............................................................................................................50 §5.2.1 什么是迭代器.......................................................................................................50 §5.2.2 使用迭代器...........................................................................................................50 §5.2.3 yield...........................................................................