Pointer vs. Reference

Question

What would be better practice when giving a function the original variable to work with:

unsigned long x = 4;

void func1(unsigned long& val) {
     val          


        

Answer 1

If you have a parameter where you may need to indicate the absence of a value, it's common practice to make the parameter a pointer value and pass in NULL.

A better solution in most cases (from a safety perspective) is to use boost::optional. This allows you to pass in optional values by reference and also as a return value.

// Sample method using optional as input parameter
void PrintOptional(const boost::optional& optional_str)
{
    if (optional_str)
    {
       cout << *optional_str << std::endl;
    }
    else
    {
       cout << "(no string)" << std::endl;
    }
}

// Sample method using optional as return value
boost::optional ReturnOptional(bool return_nothing)
{
    if (return_nothing)
    {
       return boost::optional();
    }

    return boost::optional(42);
}