Lecture Notes: Linkers, Loaders, and Libraries

Introduction to Libraries

• Definition: Libraries are ready-compiled and tested programs that can be run when needed.
• Software Libraries: These are collections of libraries, commonly used in programming languages.
• Example: The Python math library provides solutions for number-related problems.
• Windows Dynamic Link Libraries (DLLs): Used for common tasks in the Windows OS, such as displaying a "Save As" dialog.

Benefits of Using Libraries

• Efficiency: Quick and easy to integrate into programs.
• Reliability: Pre-tested and usually free from errors.
• Performance: Pre-compiled for optimized speed.

Drawbacks of Using Libraries

• Customization: Adding functionality or tweaks can be difficult.
• Transparency: Often "black boxed," meaning the implementation details are hidden.
• Maintenance: Dependence on developers to maintain and test the library.

Linkers

• Functionality: Responsible for assigning machine addresses in external call and return instructions.
• Role: Links modules and external library routines into the finished code.
• Methods of Linking:
  • Static Linking: Includes all required library code directly in the machine code, leading to large executables.
  • Dynamic Linking: Uses library code stored on the host computer, reducing the size of executables.

Loaders

• Functionality: Loads the executable program file into memory for execution.
• Dynamic Linking Role: Loads required libraries into memory at runtime.

Key Questions

• Purpose of Linker and Loader: Understanding their roles in program compilation and execution.
• Advantages of Function Libraries: Discussing benefits such as efficiency, reliability, and performance improvements for programmers.