26. OCR A Level (H446) SLR5 – 1.2 Linkers, loaders and libraries

What are libraries in the context of programming?

• Online forums where programmers share their problems

• Ready compiled and tested programs that can be run when needed

• Physical locations where code is stored

• Groups of people who write code

Answer explanation

Libraries in programming refer to ready compiled and tested programs that can be run when needed, providing pre-written code for specific functionalities.

What is an example of a built-in library in Python?

• Music playing library

• Internet browsing library

• Maths library

• Windows Dynamic Link Libraries

Answer explanation

The Maths library is an example of a built-in library in Python that provides mathematical functions and operations.

What do Windows Dynamic Link Libraries (DLLs) provide?

• Subroutines for many common tasks on the Windows operating system

• A set of common solutions for number-related problems

• A platform for developing Windows applications

• Security features for Windows

Answer explanation

Windows Dynamic Link Libraries (DLLs) provide subroutines for many common tasks on the Windows operating system, making them the correct choice.

What is one of the benefits of using libraries?

• They are pre-tested and free from errors

• They increase the size of the executable file

• They require extensive testing before use

• They are difficult to integrate into your own program

Answer explanation

Using libraries provides the benefit of being pre-tested and free from errors, saving time and effort in development.

What is a drawback of using library routines?

• They are always open source

• Adding additional functionality can be difficult

• They are not pre-compiled

• They make programs run slower

Answer explanation

The drawback of using library routines is that adding additional functionality can be difficult, as libraries may not always support the specific features or modifications needed.

What is the role of a linker in programming?

• It compresses the executable file

• It encrypts the source code

• It puts the appropriate machine addresses in all the external call and return instructions

• It designs the user interface of the program

Answer explanation

The linker puts the appropriate machine addresses in all the external call and return instructions, allowing the program to correctly reference external functions.

What is static linking?

• Linking that occurs at runtime

• Including all required code from the libraries directly in the finished machine code

• Storing compiled versions of libraries on the cloud

• A method to reduce the size of the executable file

Answer explanation

Static linking involves including all required code from the libraries directly in the finished machine code, reducing dependencies on external libraries.

What is a potential issue with dynamic linking?

• If the required libraries change or don't exist on the host computer, the program may stop working

• It is not supported by modern operating systems

• It makes the source code publicly accessible

• It increases the compilation time

Answer explanation

Dynamic linking can lead to issues if the required libraries change or are missing on the host computer, causing the program to stop working.

What does the loader do?

• It loads the executable program file into memory ready to be run

• It optimizes the program for faster execution

• It writes the source code for the program

• It links the program with its user interface

Answer explanation

The loader loads the executable program file into memory ready to be run, making it the correct choice.

What is the purpose of a linker?

• To market the finished software product

• To design the program's architecture

• To link separate compiled subroutines into your object code

• To debug the program

Answer explanation

The purpose of a linker is to link separate compiled subroutines into your object code, allowing the program to execute correctly.