例如,标准说std :: basic_string :: copy有以下声明：
size_type copy(Ch* p,size_type n,size_type pos = 0) const;
标准库的一致性实现可以实现这两个这样的功能吗？
size_type copy(Ch* p,size_type pos) const; size_type copy(Ch* p,size_type n) const;
在这个例子中,第二个版本可以跳过if(pos> size()){throw out_of_range(); }测试是第一个必要的.一个微优化,但是你仍然看到了这个例子.
解决方法
Could a conforming implementation of the standard library implement this instead as two functions like this?
是. C标准(C 03 17.4.4.4/2-3)说：
An implementation can declare additional non-virtual member function signatures within a [Standard Library] class:
— by adding arguments with default values to a member function signature; the same latitude does not extend to the implementation of virtual or global or non-member functions,however.
— by replacing a member function signature with default values by two or more member function signatures with equivalent behavior;
— by adding a member function signature for a member function name.
A call to a member function signature described in the C + + Standard library behaves the same as if the implementation declares no additional member function signatures
