2.2.1 Programming Techniques Flashcards
Name the three programming constructs.
Sequence, branching and iteration.
Which two categories of loop is iteration split up into?
- Count-controlled
- Condition-controlled
Describe how the branching programming construct works.
A certain block of code is run if specific condition is met, using IF statements.
What is recursion?
A programming construct in which a subroutine calls itself during its execution until the stopping condition is met.
What is the base case in recursion?
A condition that must be met in order for the recursion to end.
State two advantages of recursion.
- Can be represented in fewer lines of code.
- Easier to express some functions recursively than using iteration.
State a disadvantage of recursion.
- Inefficient use of memory.
- Danger if stack overflow.
- Difficult to trace.
Give two pieces of information that are stored on the call stack.
Two from:
- Parameters
- Return addresses
- Local variables
Define scope
The section of the program in which a variable is accessible.
Give two advantages of using local variables over global variables.
Two from:
- Less memory is used
- Self-contained so unaffected by code outside of the subroutine
- Take precedence over global variables with the same name
What is top-down design?
A technique used to modularise programs in which the problem is continually broken down into sub-problems, until each can be represented as an individual, self-contained module which performs a certain task.
State two advantages of a modular design.
Two from:
- Makes a problem easier to understand and approach
- Simpler to divide tasks between a team
- Easier to manage project
- Self-contained modules simplify testing and maintenance
- Greater readability
Give another name for top-down design.
Stepwise refinement
What is the difference between procedures and functions?
Functions must always return a single value while a procedure does not always have to return a value.
What does it mean to pass a parameter to a subroutine by reference?
The address in memory of the parameter is passed to the subroutine so it’s value outside of the subroutine will be updated.
