High level languages were developed to simplify programming further. Most high level languages were first created in the 1960s and 1970s when computer hardware became much more powerful and hence speed of execution was less important. High level languages use instructions which are much more like written English. Each high level instruction can do the job of many low level instructions.
Many different high level languages are available. Here are some examples :
|C++||A general purpose language which can be used for most tasks. C++ programs usually execute faster than programs written in other high level languages.|
|COBOL||Used for business applications such as customer databases.|
|BASIC||A general purpose programming language originally designed for use on home computers.|
|Logo||Developed for use in education, used to draw pictures and control devices such as a robot turtle.|
Each programming language has its own commands and structures that can be used. The allowed commands and structures are known as the syntax of the language.
Because a computer can only execute instructions that are written in machine code, a high level language program must be translated into machine code before it can be used. This task can be carried out automatically by computer software.
Advantages and disadvantages of writing a program in a high-level language are :
|Instructions are much easier to remember and use than assembly
High-level programs are much easier to understand than assembly language ones.
Fewer instructions are required to write a program than when using assembly language.
A program can usually be developed much more quickly using a high level language than an assembly language.
A program written in a high level language on one type of computer can usually be converted to operate on another type of computer quite easily. Because of this high level language programs are described as being portable.
|High-level language programs normally take up more space and execute more slowly than equivalent assembly language programs.|
GCSE ICT Companion 04 - (C) P Meakin 2004