1. Pseudocode and general stuff

Pseudocode and General Stuff

Sample Pseudocode

BEGIN
    CONSTANT StdDeduct = 10000
    CONSTANT DepDeduct = 2000
    CONSTANT Rate = 0.20
 
    INPUT GrossIncome
    INPUT NumDep
 
    TotalDeduct ← StdDeduct + (NumDep * DepDeduct)
    TaxableIncome ← GrossIncome - TotalDeduct
    IncomeTax ← TaxableIncome * Rate
 
    IF IncomeTax < 0
        OUTPUT 'Income Tax is Negative !'
    ELSE
        OUTPUT IncomeTax
    ENDIF
END

Common Pseudocode Keywords

• BEGIN / END
• INPUT / OUTPUT
• IF / ELSE / ENDIF
• FOR / ENDFOR
• WHILE / ENDWHILE
• CONSTANT
• ← — define
  • <identifier> ← <value>

Array Declaration

DECLARE numbers : ARRAY[0:3] OF INTEGER

Data Validation

Purpose

To ensure that the data entered is sensible and reasonable

Type	How it Works	Example
Existence Check	Checks if input is already in the system	Student name is in the database
Format Check	Checks if the data is in the correct format	Date in the format DD/MM/YYYY
Length Check	Checks if the length of the data is correct	Length of password
Presence Check	Checks if data is entered into a field	Username cannot be left blank
Range Check	Checks if the data value is within a certain range	Mark must be from 0 to 100
Type Check	Checks if data is of the correct type	Number must be an integer (120), not a string (“120”)
Check Digit	The last one or two digits in data are used to verify whether the other digits are correct	NRIC/FIN number

Data Verification

Purpose

To ensure the input data matches the original source

Method	How it Works	Example
Double Entry	Data is entered twice to reduce the chance of errors	Creating a new password and entering it twice to reduce the chance of typos
Proofread	Checks that entered data is as intended	Reviewing an online form before submitting to ensure the data entered is correct

Programming Errors

1. Syntax error occurs when the syntax rules in the programming language is not adhered to (e.g. error in the syntax of a sequence of characters of tokens). Program will not compile until all syntax errors are corrected.
2. Logical error is caused by wrong program design. This could happen when the algorithm for solving the program in incorrect. The program may be compiled and executed but does not give the expected output.
3. Run-time error is detected at run-time e.g. stack overflow, division by 0, open a file that does not exist.

Modular Approach

Definition

Aspect	Details
Definition	Modularity is the feature of designing a problem solution as a collection of well-defined separate modules, each serving a specific purpose and connected to the main program.
Module	A module is a complete part-program used within the main program.

Advantages

Advantage	Explanation
Encourages code reuse	Modules can be stored in a library and reused in other solutions.
Easier to debug	Modules are small and easier to test individually.
Easier to maintain and modify	Modules can be added or removed easily.
Supports teamwork	Different programmers can work on different modules simultaneously, and each module can be coded and tested separately.
Easier project management	Large projects become easier to monitor and control.

Disadvantages

Disadvantage	Explanation
Time-consuming planning	Extra time is needed to divide the problem into modules.
Larger memory usage	More memory space may be required.
Limited visibility	Programmers may not see all the code or documentation.
Over-modularisation	Too many modules can make the system unnecessarily complex.

Incremental Approach

An incremental approach solves a small version of the problem first and gradually extends the solution to larger versions instead of recalculating from scratch.

Advantages

Advantage	Explanation
Efficient testing and debugging	Small portions are added and tested step by step.
Early problem detection	Bugs can be identified and fixed early because development starts small.

Disadvantages

Disadvantage	Explanation
Code may become messy	The algorithm can become unstructured as it grows.
Harder to reuse code	The code may not be easily reusable in other algorithms.