Programming Techniques and Logical Methods (F452 OCR)

Here are 21 pages of extensive notes on the not-so-obvious bits of the OCR F452 syllabus (for the May 2010 exam).

As always, these notes were written for me to revise from, and so there may be bits that are not covered as much as you need to learn them in, or there may be bits that are covered in nauseating detail for you because you are already 100% familiar with them.

Original document is a Word 2007 (.docx) which if you want, email me and I will send you a copy.

These notes cover all six topics within Unit 2:

  1. Designing Solutions to problems
  2. The Structure of Procedural Programs
  3. Data Types and Structures
  4. Common Facilities of Programming Languages
  5. Writing Maintainable Programs
  6. Testing and Running a Solution
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  • Created by: Jackarias
  • Created on: 03-04-10 16:32
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Programming Techniques and Logical Methods
OCR F452 Written Exam (May 2010)
:: Jack Bennett, 12F
Designing Solutions to Problems (3.2.1)
Programs aim to ensure that the...
o User can input data easily
o Output is clear and understandable
Aim is to be user friendly, i.e. effective, efficient and satisfying for the end user.
Allows the user to input Comfortable for end user
and output all data Makes best use of ­ program is easy to learn:
accurately. Reduces facilities available to use of familiar tools and
potential of costly errors. the program, e.g. icons etc. Keeps down
quick processor time. training costs and
Efficient interfaces improves morale.
increase productivity
for the user.
Very often, the user interface requires data to be input using a keyboard and mouse.
Usually takes the form of a GUI (Graphical User Interface) or a form-based interface.
A number of factors should be considered when designing an input screen...
o The user ­ age, computer literacy, disabilities etc.
o Layout ­ using headings, not cluttering but using all space etc.
o Order ­ heading at top, action buttons (in forms etc.) at bottom
o Validation ­ interface should reject invalid data
o GUI objects ­ objects should make data input efficient / avoid errors
o Online help ­ interface should keep user informed (progress bars etc.)
Data capture forms are used to collect data to be input into a program.
o Layout ­ data fields should match / correspond to paper version
o Instructions ­ no validation checks on paper; clear instructions essential
o Readability ­ if data cannot be read, it cannot be input (encourage CAPITALS)
Reports are presentations of data ­ must consider...
o The user ­ age, computer literacy, disabilities etc.
o Type of output ­ often a pie chart can be clearer than text, for example
o Title ­ report may be stored and later read out of context; heading essential
o Date ­ representative of data at a specific time; date should be included
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Programming Techniques and Logical Methods
OCR F452 Written Exam (May 2010)
:: Jack Bennett, 12F
When designing other types of interface, such as touch screen interfaces, other
factors must be considered. For example, the contact areas must be large enough on
the touch screen to be used effectively.
People with disabilities should also be catered for, for example, by adding sound
output in addition to the visual output.
Remember that programs do not necessarily run on a computer.…read more

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Programming Techniques and Logical Methods
OCR F452 Written Exam (May 2010)
:: Jack Bennett, 12F
There are many advantages to modular design:
1. Program is easier to write and test.
Each module is small and can be written independently.
2. Design clearly shows how different parts of program relate.
Reduces errors caused by different parts of a large program.
3. Programmers working on separate modules can easily develop the program.
Modules can be allocated according to expertise of programmer.
4.…read more

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Programming Techniques and Logical Methods
OCR F452 Written Exam (May 2010)
:: Jack Bennett, 12F
o Use lowercase letters with code close to English.
o Indent as appropriate.
Rapid Application Development is a method for designing and writing software.
It produces successive prototype versions of the software.
This continues to happen until the final version is produced.
RAD is similar to the spiral model.
o Several increasingly refined prototypes are created.
To solve the problem, programmers produce a prototype with reduced functionality.…read more

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Programming Techniques and Logical Methods
OCR F452 Written Exam (May 2010)
:: Jack Bennett, 12F
Disadvantages of RAD include:
1. Not efficient when dealing with large-scale projects.
Initial prototypes dynamically different from final product.
2. Focuses on end result rather than on the processing.
Can produce solutions that are inefficient in their use of resources.
The Structure of Procedural Programs (3.2.2)
These are short definitions of key terms for structures of procedural programs.
Statement ­ single instruction or step within a program.…read more

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Programming Techniques and Logical Methods
OCR F452 Written Exam (May 2010)
:: Jack Bennett, 12F
WHILE REPEAT UNTIL
Condition is tested before each cycle. Condition is tested after each cycle.
Instructions may never be executed. Instructions will always be executed once.
In both cases, it repeats if the condition is TRUE and exits if the condition is FALSE.…read more

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Programming Techniques and Logical Methods
OCR F452 Written Exam (May 2010)
:: Jack Bennett, 12F
Instructions are then executed using the actual values substituting parameters.
This is referred to as `passing parameters' to the procedure.
Recursion is when a subroutine calls itself.
The subroutine is executed as normal until it gets to the
line where it calls itself.
o If a new subroutine is started every time the
subroutine is called, the process would go on
indefinitely.
Therefore a recursive subroutine usually has parameters.…read more

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Programming Techniques and Logical Methods
OCR F452 Written Exam (May 2010)
:: Jack Bennett, 12F
Iteration Recursion
Uses a loop to repeat instructions. Repeats by calling itself with
simplified arguments.
End condition to the loop decides
when to stop looping. Stopping condition causes subroutine
to terminate without calling itself.
Must include instructions that move
a tracking variable towards the end Simplified arguments used in the
condition. recursion eventually lead to the
stopping condition.…read more

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Programming Techniques and Logical Methods
OCR F452 Written Exam (May 2010)
:: Jack Bennett, 12F
Data structures allow us to store more than one item of data together.
o Under one identifier (name).
Can be used to access individual items of data.
Two data structures ­ arrays and records.
Arrays contain several items of data.
Used to group variables of the same `category'.
Actual data stored in the memory is called an element of the array.
The number after the array is called the index...…read more

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Programming Techniques and Logical Methods
OCR F452 Written Exam (May 2010)
:: Jack Bennett, 12F
New data is simply added to the end of the file.
This is known as appending the data.
To search for data you need to start from the first item.
By then searching each item in turn, you will find the record you are looking for.
You need to confirm whether the item you are searching for exists in the file.…read more

Comments

Sean Keegan

Thank you very much!  I have used both of the resources you have made for AS and they have been more than useful. Thanks again buddy.

Pink198

Thank you so much. My college has a resources area that is normally stacked with information, but on this unit it had nothing at all, only excercises "write a program that outputs..." with no revision notes at all, this saved me :)

Chloe


Thankyou thankyou thankyou! Both resources helped me understand it so much better. Its so much friendlier when its written by a yr12 :) THANKYOU! :D

Kaya Katana

My teacher always told us to use this before I even found this site. Thanks a lot for uploading it for others though xDD. It's really pretty~

Rebecca Fields

Thank you! 

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