What are the different types of linking and loading?

The different types of linking and loading are static linking, dynamic linking, load-time dynamic linking, and run-time dynamic linking.

Static linking is a process in which the linker combines all the relevant code from libraries directly into the executable file. This happens at the time of compilation. The advantage of static linking is that the executable file can run independently, without needing any additional libraries at run-time. However, it can lead to larger executable files and potential wastage of memory, as all the library code is included, whether it's used or not.

Dynamic linking, on the other hand, does not include the library code in the executable file. Instead, references to the library functions are included. The actual linking with the library code happens at run-time, when the application is executed. This results in smaller executable files and efficient memory usage, as only the required library code is loaded. However, the necessary libraries must be available on the system at run-time.

Load-time dynamic linking is a variant of dynamic linking. In this case, the linking still happens at run-time, but it is done when the program is loaded into memory, before execution begins. This means that the necessary libraries must be available at load-time. If a library is not available, the program will not run.

Run-time dynamic linking is another variant of dynamic linking. In this case, the linking happens during the execution of the program. This allows a program to decide when and if a certain library is needed, and to load it only when necessary. This can provide additional flexibility, but it also requires more complex programming, as the program must handle the loading and linking of libraries itself.

In summary, static linking and dynamic linking are the two main types of linking, with load-time dynamic linking and run-time dynamic linking being variants of dynamic linking. Each type has its own advantages and disadvantages, and the choice between them depends on the specific requirements of the program and the system it will run on.