More Recursion

Objectives

1. Continue to learn about recursion.

Notes

• We discussed the recursive exponential program and implemented it.
• We discuss the layout of a program in memory

  • Address	Use
    High Memory	Stack
    	Heap
    	Uninitialized data
    	Initialized data
    Low Memory	Text (code)

  • The stack is where functions store information
  • The heap is where dynamic memory is stored
  • The data segments are where global variables are stored.
  • The text segment is where the code is stored.
• There may be other memory used by the OS
  • But that is not important now.
  • More in operating systems
• Each time a function (including main) is called
  • An activation record or stack frame is pushed onto the stack.
  • This contains
    • The local vriables
    • The return address for the function
    • Other information.
    • More in architecture/operating systems/assembly
• When a function exits, it removes the activation record from the stack
  • After it restores any information stored in that recored.
• This explains
  • Lifetime and scope of a variable.
  • How recursive calls each have their own copy of a variable.
• We looked at the Fibonacci sequence
  • Or $fib(n) = \begin{cases}fib(n-1)+fib(n-2), & n > 2\\ 1, & n =1,2\end{cases}$
  • And created the program fib.cpp