int square(volatile int* &ptr)和int square(volatile int*ptr)两个传参到底有什么区别?

2360985396

int square(volatile int* &ptr)和int square(volatile int*ptr)两个传参到底有什么区别?

eric2013

int square(volatile int*ptr) //passed by value
{
   ptr++; // change will be discarded once function returns
}

int square(volatile int* &ptr) //passed by reference
{
   ptr++; // change will persist when function returns
}