programming techniques

Question 1

sequence

Answer 1

set of program instructions are written and exceted in the order that they are written in

e,g
name = input(“please enter name: “)
print(“ shush” +name “.”)

Question 2

branching(selection)

Answer 2

allows a program to run sequences if code depending if the condition evaluates to true of false

carried out with if/else and switch/case

Question 3

iteration

Answer 3

section of code is repeated using a loop
can be controlled with a condition at the start or end of loop

Question 4

features of iteration

Answer 4

count controlled:
definite iteration which is a for loop

condition controlled: indefinite iteration which is a while loop(loops till condition is met)

pre check checks condition before executing statements
pro check executes the statement and then checks the condition

Question 5

recursion

Answer 5

when a function calls itself from within the function

Question 6

benefits and drawbacks of recursion

Answer 6

benefit:
more natural to read
faster to write as less lines of code
suited for certain problems e,g trees
can reduce size of problem with each call

drawbacks:
Requires more memory than the equivalent iterative algorithm
More difficult to trace as each frame on the stack has its own set of variables
Usually slower than iterative methods due to maintainence of the stack
Can run out of stack memory due to too many calls causing it to crash

Question 7

global variables

Answer 7

can be accessed throughout the program
they are declared or set outside any subprograms and subroutines

dangerous as it is easy to overlook themwhen they are changed
make debuggin hard

Question 8

drawbacks of global variables

Answer 8

Global variables make it difficult to integrate modules
they increase complexity of a program
they may cause conflicts with names written in other modules
makes debuggin harder

Question 9

local variables

Answer 9

are set or declared within a function or a subprogram
can only be accessed from with that subprogram
can be used as a parameter

Question 10

IDE

Answer 10

set of tools to develop a program

Question 11

Features of IDE

Answer 11

Error diagnostics - can locate and report errors
Code can be examined as it is running which allows logical errors to be pinpointed
Debugging tools allow inspection of variable values this can allow run-time detection of errors

Question 12

IDE - Breakpoints

Answer 12

Use to test the program works up to specific points
Check variable contents at specific points
Can set a point where the program stops running

Question 13

IDE - stepping

Answer 13

Can set the program to run line by line
Slow down/watch execution
Find the point where an error occurs

Question 14

modularity

Answer 14

programs are written in separate sections as it is easier to test

Question 15

functions

Answer 15

are subprograms which can return a value but not always

Question 16

procedures

Answer 16

perform opeartions but do not reurn values

Question 17

parameters

Answer 17

variables that usually have brackets
can be passed by value or by reference

by value:(default)
a copy is made in the subprogram,so changing the value in the subprogram does not change the original value

by ref:
address of the variable is passed to the subprogram
if the variable is changed by the subprogram it stays the same