C TemplateCornerCases计算机等级考试

文章作者 100test 发表时间 2010:01:01 12:14:50
来源 100Test.Com百考试题网

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　　Following are some corner cases of C template features. A lot of the text is simply extracted from "C Templates: The Complete Guide", with some of my personal understanding. These features are trivial and easily neglected, but you should have some impression to them in case you run into troubles caused by the neglect.
　　I made my notes in English, and I dont bother to translate them into Chinese, forgive my laziness.
　　0. use "typename" to extract type defined within a type parameter, like this: typename T::iterator itr. otherwise the itr is treated as a data member of T.
　　1. zero initialization
　　When using a var x of type T, we MUST initialize it like this: T x = T(). so that when T is a primitive type, x can also be initialized with 0, or NULL (when T is a pointer type). Of course we must make sure
　　when T is a class type, it has a default constructor. Simply using T x. cant initialize x when T is a primitive type.
　　2. .template
　　The .template Construct
　　A very similar problem was discovered after the introduction of typename. Consider the following example using the standard bitset type:
　　template