You could use a pointer instead of a reference if:

    • Null is a valid return value
    • You dynamically constructed something in the function, and the recipient becomes the owner. (In this case, you might consider returning a smart pointer such as std::unique_ptr or boost::shared_ptr.)

    Regardless, you would not want to return either a pointer or a reference to a local variable.

    1. int& something(int j)
    2.   {
    3.       int* p = 0 ;  
    4.       return *p;
    5.   }
    7.   void main()
    8.   {
    9.       int& i = something(5);
    10.       i = 7;   // run-time error 
    11.   }

    在上面的代码中，由于引用不能指向NULL，因此如果p指向NULL，那么便会产生异常。除非可以确保p一定产生了有效的数据。否则不要讲pointer作为引用的返回值。

    https://stackoverflow.com/questions/7813728/pointer-vs-reference-return-types