What is the difference between struct node *tmp and struct node **tmp in data structures? If possible show with example.

Answer 1

One is a pointer to a struct, the other is a pointer to a pointer. The first let's you pass it to a function and allow the function to modify the contents of the original object. The second allows you to do that or to assign a new struct to the variable that will then be passed back out of the function.

Answer 2

Ok.