CEG 221 Lesson 6: Using

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CEG 221Lesson 6 Using Building Libraries

• Mr. David Lippa

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Overview

• Building Libraries
• What are libraries?
• Why build libraries?
• How to build libraries
• Using Libraries
• Tradeoffs
• Questions

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What are libraries?

• A library is a collection of data structures and
  functions that are grouped together by relevance
  with a specific purpose in mind
• Precompiled library a header file containing
  function prototypes and a .LIB file consisting of
  their function bodies the header file is said to
  be the interface
• kernel32.lib is a precompiled library of routines
  and structures used to make an application run
  under 32-bit Windows
• Uncompiled library a library consisting of
  header files (.h) and C source files (.c)
• stdio.h is an uncompiled library of structures
  (FILE) and functions (printf, scanf, etc.) for
  user input/output

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Why Build Libraries?

• They add an extra layer to modular programming
  a module that is a collection of modules
• They are portable (cross-platform) when
  distributed as source files and let you build
  them on whatever platform (OS) is needed with
  whatever compiler
• They hide the headers/interface (how to use) from
  the source/implementation (the actual work)

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Precompiled Libraries

• Precompiled libraries come with a .LIB file and
  header files that specify how to use the library
• They are platform-specific it must be properly
  compiled on the same processor type (ie. x86),
  OS, and compiler
• They need to be linked with your application, and
  their header files must be included in the project

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Uncompiled Libraries

• Uncompiled libraries come with complete source
  code
• Consists of header files (.h) which consist of
  data structures and function prototypes
  (interface) and source files (.c) which consist
  of function bodies (implementation)
• They either need to be
• compiled into a .LIB file and then linked
• included in the project with the rest of your
  source files

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Examples

• Libraries of Libraries Red Hat Linux an OS
  that has libraries and header files built into
  the operating system to build the next version of
  that operating systemx
• JPG, HDF Libraries for importing images
• Windowing Toolkits (QT, MFC) for building
  Graphical User Interfaces and applications
• Groupware Toolkits for building
  Groupware/collaboration applications
• Precompiled Library Demo Integration

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Advantages and Disadvantages

• Precompiled
• PROS Just link, add header files, and run!
• CONS Compiler, Processor, and OS-specific

• Uncompiled
• PROS cross-platform, easier to debug
• CONS more difficult to use difficult to debug
  if it fails to compile

• When looking for a library, it is typically best
  to get a precompiled library for a novice user
• Both types typically come with documentation on
  how to use the library and what each function does

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Questions?