Linkers, Loaders and Use of Libraries

Question 1

Linkers

Answer 1

This is a piece of software that is responsible for linking external modules and libraries included within the code.

Question 2

How do static linkers work?

Answer 2

Modules and libraries are added directly into the main file. This increases the size of the file. Any updates to modules and libraries externally will not affect the program. This means a specific version of a library can be used.

Question 3

How do dynamic linkers work?

Answer 3

Addresses of modules and libraries are included in the file where they are referenced. When the program is run, the loader retrieves the program at the specified address so it can be executed.

Question 4

There are two types of linker:

Answer 4

Static and Dynamic

Question 5

What are the advantages of using dynamic linkers

Answer 5

The advantage here is that files remain small and external updates feed through to the main file; there is no need to rewrite the code.

Question 6

What are loaders and what do they do?

Answer 6

Loaders are programs provided by the operating system. When a file is executed, the loader retrieves the library or subroutine from the given memory location.

Question 7

Use of Libraries

Answer 7

Libraries are pre-compiled programs which can be incorporated within other programs using either static or dynamic linking.

Question 8

What are the advantages of using libraries?

Answer 8

They are ready to-use and error free, so save time developing and testing modules.

They can be reused within multiple programs.

Provide a specialised range of functions which would otherwise require a lot of time and effort to develop, so save programmers from having to ‘reinvent the wheel’ and instead make use of others’ expertise.