Programming Next Steps

• Stack frames are used to store return addresses, parameters and local variables for subroutine calls
• Every time a subroutine is called, it is pushed onto the stack as a stack frame
• When a subroutine is finished, the stack frame is popped from the stack to retrieve the return address
• Subroutines help reduce repeated code for frequently used operations, which also makes code easier to read
• A function returns a value, a procedure does not
• Subroutines are out of line blocks of code which are not defined within the main body of code
• Parameters are used to pass data into and between subroutines. The specific value passed in is called an argument.
• Parameters may be required or optional, or not needed at all depending on the subroutine
• Global variables are declared at the top of the program outside any subroutines. They can be used anywhere, and exist as long as the program is running
• Local variables are declared within subroutines and are stored on the call stack. They are destroyed once the subroutine ends.
• Local variables are more memory efficient and are better for multi-person projects
• Exception handling allows programs to 'try' code that may crash due to erroneous input, and 'catch' any errors that occur, carrying out a separate set of tasks and returning to operating as normal
• A recursive subroutine calls itself within its own subroutine, and has a stopping condition (a base case)
• If a recursive subroutine doesn't have a base case, it will never terminate and a stack overflow will occur
• Many recursive solutions can also be implemented using iteration. Recursion may allow for more compact code; iteration may be less memory intensive