teach-ict.com logo

THE education site for computer science and ICT

2. Libraries

A code library is a collection of compiled procedures that can be used for common tasks.

Procedures are sections of code within a program that carry out a specific task. Many of these tasks are common across different programs. Because of this, programmers have created libraries.

A library is a file that contains a number of useful procedures.

Libraries come with documentation which details everything a programmer needs to know in order to use the procedure. The documentation describes how the procedures can be called, the inputs required, and what is returned when the procedure is completed. Specialist code libraries can be purchased as products in their own right.

The Windows operating system, comes with an extensive library of ready-to-use code. This code is held within a number of DLL files - short for Dynamic Link Library. Programs written to run in Windows will make extensive use of these libraries.

You are probably very familiar with what is shown in the image below: a prompt asking you to select a file from a directory. Similar interfaces can be found in many Windows applications, and they all make use of the same 'open and select' procedure, included in a DLL library file.

open and select file


Challenge see if you can find out one extra fact on this topic that we haven't already told you

Click on this link: What is a code library