constness and pointers to pointers

Question

I\'m very much confused about the const keyword. I have a function accepting an array of strings as input parameter and a function accepting a variable number o

Answer 1

You cannot pass char ** into const char ** because the compiler cannot guarantee const correctness.

Suppose you had the following code (and it compiled):

void foo(const char **ppc, const char* pc)
{
  *ppc = pc; // Assign const char* to const char*
}

void bar()
{
  const char c = 'x';
  char* pc;

  foo(&pc, &c); // Illegal; converting const char* to const char**. Will set p == &c
  *pc = 'X';    // Ooops! That changed c.
}

See here for the same example without the function calls.