Pointers - variables that store a location

What default value should be used to initialize a pointer if declared 
before it is known where it should point?
Write a line of code that declares a pointer to an array of characters
Write a line of code that declares a local array of 100 integers
Write a line of code that frees the memory pointed to by variable arr
Write a line of code that dynamically allocates an array of 100 integers
Write a line of code that assigns the pointer pt to point to the variable x
Write a line of code that changes the value pointed to by pt to be 5

Write a function, e.g. swap, that exchanges the value of two variables.
Write it in such a way that the values in the variables in the caller's
space are changed (rather than only the inputs to the function).