2.1.2- designing, creating and refining algorithms

Write a program to calculate the volume of a fish tank based on its dimensions and report the results back to the user

identify the

-input

-process

-output

• input- length:real/float

  height:rela/float

  width:real/float

• lengthxheightxwidth

• output: volume:real/float

write a program that will ask the user for the number of students in their class and then prompt to enter each their test scores in a range 0-100. It should then output the highest, lowest and average score to user

identify

-input

-process

-output

-NumofStudents:integer

CurrentScore:integer

-process-TotalScore=TotalScore+CurrentScore

AverageScore=TotalScore/NumOfStudents

store list of scores in an array and loop through array and return min score and max score

-output; MinScore:integer

MaxScore:Integer

AveScore:real/float

Input

-anything which needs to be supplied to the program so that it can meet its goals

-often input from the users

-consider an appropiate variable name and data type for the input

processes

-consider what calculations need to be performed while the program is running

-does data need to chnage formats or data types

output

-consider what your program needs to output

-consider what form this output needs to take -consider an appropiate variable name and data type for any output

what are structure diagrams

-illustrate problem decomposition

-can be used for developers to understand a problem to code and and to share with users during systems analysis

-produced using a method called step-wise refinement

-lowest level of nodes should achieve a single task

what are pseudocodes

text-based way of representing the sequences of steps in an algorithm without worrying about the syntax or rules of a particular language

state the flowchart symbols

what is a global variable

identifies a variable that can be used in a subroutine or function instead of it being declared inside the function or subroutine which would only make it available to a particular function

constants

these are values that don’t change throughout the life of the program

-do not say that they are variables

difference between while loop and do loop

a while loop will not necessarily have its code executed but the condition is checked at the beginning of the statement, whereas with the do loop the code inside the loop will execute at least once because the condition is checked at the end of the statement

memorise ocr exam reference language

okay

what are the two main types of error

-syntax

-logic

what are syntax errors

are errors which break the grammatical rules of the programming language

-they stop it from being run/translated

what are logic errors

errors which produce unexpected output

-on their own they won’t stop the program running

const voting_age=18

your_age=(input(“how old are you?”))
if (your_age>=voting_age) then

print(“you are old enough to vote”)

else

print(“you are not old enough to vote”)

endif

-spot what the error is

-is it syntax or logic

-missing a type conversion from string to integer

-syntax error

what are trace tables

typically involves examining a printed extract of program code and running through the program