Question

Suppose I have this code. Your basic “if the caller doesn’t provide a value, calculate value” scenario.

void fun(const char* ptr = NULL)
{
   if (ptr==NULL) {
      // calculate what ptr value should be
   }
   // now handle ptr normally
}

and call this with either

fun();          // don't know the value yet, let fun work it out

or

fun(something); // use this value

However, as it turns out, ptr can have all kinds of values, including NULL, so I can’t use NULL as a signal that the caller doesn’t provide ptr.

So I’m not sure what default value to give ptr now instead of NULL. What magic value can I use? Does anybody have ideas?

Answer 1

void fun()
{
   // calculate what ptr value should be
   const char* ptr = /*...*/;

   // now handle ptr normally
   fun(ptr);
}