warning: passing argument x of 'xyz' from incompatible pointer type

Question

If a variable is declared as:

char ** argv; 

And a function's definition is something like:

extern int my_system(const char *argv[]);

Now if we are passing the argument in the function as:

(my_system(argv))

then it throws the warning passing argument 1 of 'my_system' from incompatible pointer type.

What can be the possible solution to this?

Answer 1

In C, there is no implicit conversion between T** to const T**, because it would not prevent modification of ultimate element in all cases. See C FAQ's question 11.10 for enhanced explanation and example of "backdoor" modification.

In your case, gained understanding of intricacies, you could cast the pointer to silent the warning:

extern int my_system(const char *argv[]);

int main(int argc, char* argv[])
{
    my_system((const char**)argv);
}