3.2.2 Custom-designed logic used in software solutions

Students Learn About

  • requirements to generate these include:
    • – identification of inputs, processes and outputs
    • – representation as an algorithm
    • – testing of the logic in the algorithm
    • – identification and definition of required data structures
    • – use of data structures, including multidimensional arrays, arrays of records, files (sequential and relative)
  • customised off-the-shelf packages
    • identifying an appropriate package
    • identifying the changes that need to be made
    • identifying how the changes are to be made
Students Learn To:

•       document the logic required to solve problems, including:

  • nesting of control structures
  • record structure
  • the use of files (sequential and relative)
  • random number generators
  • arrays of records
  • multidimensional arrays

•       develop a suitable set of test data

•       desk check algorithms and source code that include complex logic

•       select an appropriate data structure to solve a given problem

Student Activity

Review each Standard Algorithm and create code to implement them

Sample code:

#-------------------------------------------------------------------------------
# Name:        Writing Dictionaries to File
# Purpose:
#
# Author:      jlai
#
# Created:     26/02/2018
# Copyright:   (c) jlai 2018
# Licence:     <your licence>
#-------------------------------------------------------------------------------
import json
from collections import OrderedDict

# Use OrderedDict to maintain the order of the elements
personArray = OrderedDict()

def uploadFile():

    ##Keep loading into Dictionary until no Person ID entered

    ##Note: the use of nested WHILE loops - look at use of BREAK to terminate loops
    while True:
        finish = False
        ## Request entry of a Person ID - must not already exist - or blank to finish

        ## Note: use of WHILE TRUE (infinite loop) and BREAK (to finish loop) allows
        ##      the use of WHILE as a "Pretest" or "Post-Test" Loop
        while True:
            personId = input("Person Id")
            if personId == "":
                finish = True
                break
            else:
                if personId in personArray:
                    print("Try again - person id already exists")
                else:
                    person = OrderedDict()
                    break
        if finish:
            break

        ## input the corresponding Person Information for the nominated Person ID
        personName = input("Person Name").lower().strip()
        personDOB = input("DOB")

        ## put the details into a "RECORD" - using a Python Dictionary to do this
        person = {
                'name' : personName,
                'DOB': personDOB
        }

        personArray[personId] = person

    ## Using JSON to save the OBJECT to FILE
    print(f'Create {personArray}')
    with open('data.json','w') as f:
        json.dump(personArray, f)

def unloadFile():

    ## Retrieve the OBJECTS from File using JSON
    ## - in this case I specify the OrderedDict Collection object
    ## This then returns the items in the correct order

    with open('data.json','r') as f:
        personArray = json.load(f, object_pairs_hook=OrderedDict)

    #print(personArray)

    ##print out elements of OrderedDict
    #for person in personArray:
    #    print(person,personArray[person])

    searchName = input("What name/part of name to search for?").lower().strip()

    for personId, person in personArray.items():
        personName =  person['name']

        if searchName in personName:
            print(f"found '{searchName}' in '{personName}'")

        personDOB = person['DOB']
        print(f'{personId} - {personName} - {personDOB}')

def main():
    ## ask upload a new file?
    if input("Upload New File? (Y/N)").upper() =="Y":
        uploadFile()

    ## process contents of file
    unloadFile()

if __name__ == '__main__':
    main()








ċ
arraysRecordsJSON.py
(1k)
Joseph Lai,
26 Feb 2018, 06:41
v.1
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