passing arg 1 of `foo' from incompatible pointer type

Question

Why this shows warning:

#include
foo (const char **p)
{ 

}

int main(int argc , char **argv)
{
    foo(argv);
}

But following

Answer 1

In the first version you are casting between two different types of pointer not simply adding a const to the pointer.

• char ** is a pointer to a (pointer to a char)
• const char ** is a pointer to a (pointer to a const char)

As you can see these pointer point to different types similar to the more obviously questionable:

int *i;
double *d;
d = i;

In your second example you see that you can cast from a pointer to a const pointer so if you were to apply this to your situation you would need to have a const pointer to (a pointer to a char).

foo(char * const *p);