Programming

Programming

1. Algorithms

   • An algorithm is a step-by-step approach to solving a problem. It is written in pseudocode.
     • Pseudocode is independant of any particular programming language
     • Psuedocode is an outline of any code or a complete program that can be easily converted to a particular programming language
   • Flow charts are a series of symbols and connecting lines to represent each step of an algorithm

2. Programming languages

   • Machine code is a set of binary instructions that are used by the CPU to perform a task
   • High level code is a computer programming language based on natural language or mathematical notation
   • An assembler is the source which which is written in assembly language
     • It translates source code into machine code that the computer can understand
     • It is an efficient low-level language that can be translated quickly
     • It is different to write and takes many programmers and a lot of time
   • Compilers are source code created by the programmer that is not understandable by the computer
     • They convert source code into object code
       • Object code is converted to match the target computer that will run the software
       • An advantaged of compilers is that they create a executable file which runs without source code
       • A disadvantage is the method of compilation of a large program takes a long time to complete
   • Interpreter software normally executes source code directly
     • It runs slower than compiled software
       • It allows the programmer to make frequent changes during development
       • The interpreter must be loaded on the target computer
   • An integrated development environment provides a range of tools for computer programmers to develop high-level language software

3. Imperative languages

   • If Then and Else are used when decision logic can have two statements
   • If statements are used when decision logic makes only one statement
   • Case statement's are used when the same decision logic can have different results

4. Handling Data in Algorithms

   • Constants are used where data that is used in a computer program is pre-set and does not change
   • Literals are values used in a computer program as themselves
   • Identifiers are where data stored in a computer system is given a symbolic name
   • Characters can consist of any single alphanumeric character
   • Integers can be any whole number
   • Real data are numbers that use a decimal point
   • Boolean data types are used for logical operations
   • String data can be used to store any alphanumeric character or string
   • Programmers use compilers to detect if incorrect data types are being used
   • Common operations consist of arithmetic and comparison operations
   • Boolean expressions are used to give Boolean logic and output either true or false
   • Logical operators are AND, OR and NOT
   • Arrays are made up of a series of array elements that are all the same data type

5. Testing

   • Syntax errors occur when the appropriate symbols and keywords are not included in code
     • These are found when the program is being compiled
     • These errors are often easy to fix
     • A test plan is a table consisting of tests that need to be carried out
       • Test data is used to test a system for errors and consists or valid, invalid and erroneous data
   • Logic errors are when a program produces an output that is incorrect or not expected
     • These are normally a result of mistakes made by the programmer
     • These errors are difficult to detect and correct