Programming

Programming

1. Algorithms

   • Pseudocode is not a programming language, it is a simple way of describing a set of instructions that does not have to use specific syntax.
   • A flowchart is a type of diagram that represents an algorithm, workflow or process, showing the steps as boxes of various kinds, and their order by connecting them with arrows.
   • Input A Input B A+B=C Output C

2. Programming Languages

   • High level code is easier for humans to understand where as machine code is only what code they can read
   • Translators are needed to transfer high level code in to machine code so the machine will be able to understand it
   • Compiler : Compilers are used to convert high level languages (like C, C++ ) into machine code . Assembers : Assembler are used to convert assembly language code into machine code. Interpreter : An interpreter is a computer program which executes a statement directly
   • Translator. This compiles or interprets the code. Auto documentation. This explains the function and purpose of the code, eg by noting the modules and variables used, and its expected behaviour, and collates this into a text file that can be used by other developers to understand how and why the code was created.

3. Control flow in imperative languages

   • It is crucial that the steps in an algorithm are performed in the right order - otherwise the algorithm will not work correctly.
   • At some point in an algorithm there may need to be a question because the algorithm has reached a step where one or more options are available. Depending on the answer given, the algorithm will follow certain steps and ignore others.
   • Iteration in programming means repeating steps, or instructions, over and over again.

4. Handling data in algorithms

   • Data values that stay the same every time a program is executed are known as constants. Constants are not expected to change. Variables are data values that can change when the user is asked a question, for example, their age. Variables may change during program execution.
   • Integer (whole number): 4, 27, 65535 Real (decimal number): 4.2, 27.4, 5.63 Boolean: true or false (form of 1&0) Character: a, F, 3, $, £ String: abc, hello world
     • True or false questionnaire: Boolean and String
   • Examples of one-dimensional arrays: List of temperatures recorded every hour in a day , or a month, or a year. List of employees in an organization List of products and their cost sold by a store Table of daily rainfall data

5. Testing

   • Syntax errors - Errors in spelling and grammar. You can use the compiler or interpreter to uncover syntax errors. You must have a good working knowledge of error messages to discover the cause of the error.
   • Logical errors - Errors that indicate the logic used when coding the program failed to solve the problem. You do not get error messages with logic errors. Your only clue to the existence of logic errors is the production of wrong solutions.
   • Valid: outcome is right. Invalid: Data is accepted but is wrong. Erroneous: A piece of data that should fail