Why use double indirection? or Why use pointers to pointers?

Question

When should a double indirection be used in C? Can anyone explain with a example?

What I know is that a double indirection is a pointer to a pointer. Why would I ne

Answer 1

Simple example that you probably have seen many times before

int main(int argc, char **argv)

In the second parameter you have it: pointer to pointer to char.

Note that the pointer notation (char* c) and the array notation (char c[]) are interchangeable in function arguments. So you could also write char *argv[]. In other words char *argv[] and char **argv are interchangeable.

What the above represents is in fact an array of character sequences (the command line arguments that are given to a program at startup).

See also this answer for more details about the above function signature.