Dynamic Link Library (DLL) is translated from English as "dynamic link library". A DLL is an executable file that performs the functions of a shared library. Through its dynamic linking, DLL provides a way to call a function that is part of the executable code.
The executable function code itself is in a DLL, which contains several compiled, linked and stored functions in the processes being used. DLL serves to simplify the process of sharing sources and data. It allows applications installed on the system to access multiple contents of a single copy of the DLL loaded into memory at the same time.
Modular coding - the ancestor of DLLs
The beginning of work on the creation of a DLL can be considered the emergence of such a programming method as modular coding. At one time, modular coding greatly facilitated the work of programmers, making it possible not to write the same code for each new program several times. All simple programs contain a lot of similar code, which they began to design in the form of modules, adding them to new applications. For a while, modular coding was the simplest and most effective solution and had only one drawback. Identical modules added to programs took up disk space, which was scarce in those days.
The problem of wasting disk space on identical modules was the only one, while there were only single-tasking operating systems. With the advent of multitasking operating systems such as Windows, another problem arose. Now programs with modules with the same code, when launched simultaneously, began to load it into RAM, “eating up” all the resources. It is worth noting that at that time, a 500 megabyte memory module was the largest available and it was quite expensive. But even the maximum size of the RAM did not save users, the programs loaded the RAM completely, making the normal operation of the computer impossible.
The emergence of DLLs
A worthy solution to these problems was found, it looked like this: modules with the same code ceased to dock with the main program, saving them into a separate executable file, which could be accessed by any application as needed. It is this solution that forms the basis of DLLs that dynamically link to any program. Now it is possible to store executable code in these libraries in the form of functions or procedures, graphics and even videos, which made it possible to save disk space and RAM resources.
The only drawback of dynamic link libraries is the waste of extra time loading the program. In addition to this minor drawback, DLL consists of advantages alone. Therefore, these libraries are widely used and are used by programmers in almost every application.
