Tools

Tools

1. High Level Languages

   • A high level language is a programming language that allows code to be written. It is similar to a natural human language, such as Welsh or English. Some programmers prefer to use high level programming languages as they are easier to understand, learn and program. Their commands are similar to natural languages like English or Welsh and identifiers can be long and meaningful. High level programming languages also allow the use of powerful commands that perform quite complex tasks such as MsgBox in Visual Basic or the SORT clause in COBOL. High level languages are used when the execution speed is not critical, e.g. in common productivity applications, such as a word processor. Examples of common high level programming languages include:

2. Machine code

   • Machine code is the opposite of a high level language in that it does not resemble any natural language and is made up entirely of bit patterns (instructions or data) that can be executed directly by the CPU. Examples of machine code instructions are opcodes and operands, discussed on pages 31–2. High level languages have to be converted into machine code before they can be executed by the CPU. For further discussion see pages 66–7. Although highly uncommon, some programmers may wish to program directly in machine code. This is primarily done when programming device drivers or where a fast execution speed are critical.

3. Variables

   • In computer programming, a variable may be required to store data that can change. Variables are given identifiers (names) that should reflect the data being stored in them. An example of a variable is txt_FirstName. This variable has a self-documenting identifier, which implies the type of data being stored in it is text containing a person’s first name.

4. Constants

   • Constants are used in computer programming to store data that does not change. Constants are also given self-documenting identifiers that should reflect the data being stored in them. An example of a constant would be Pi = 3.14, as this is a self-documenting identifier that does not change.