Static vs. Dynamic Linking: What's the Difference and When Should I Use Each?

Static link and dynamic link: differences and applicable scenarios

In the field of software development, especially when using languages ​​such as C, C and C#, we often encounter the concepts of "static linking" and "dynamic linking". The two terms refer to different ways of combining individual code modules into a complete executable program.

Compile and link

The process of converting source code into an executable program consists of two main stages: compilation and linking. Compilation converts source code into object modules, and linking combines these object modules to form the final executable file.

Static link

When a code module is statically linked, its contents are physically embedded into the executable program during the linking process. This means that the code of the linked module becomes an integral part of the executable program and cannot be modified without recompiling and relinking the entire program.

Dynamic link

Unlike static linking, dynamic linking defers the linking process until runtime. Instead of embedding the linked module's code into the executable, it contains a pointer to the module. When an executable is run, the operating system dynamically loads the module into memory and links it with the main program. This enables the flexibility to update linked modules without recompiling and relinking the entire program.

Advantages and Disadvantages

Static linking has the advantage of creating compact, self-contained executables that are independent of external modules. However, it limits flexibility and makes updating individual modules more difficult.

Dynamic linking provides flexibility and simplifies updates because linked modules can be updated or replaced without recompiling or relinking the entire program. However, it introduces dependencies on external modules, which can cause potential problems if these modules are missing or corrupted.

Example

To illustrate the difference between static and dynamic linking, consider the example of compiling the main program:

Static link:

<code><br>|-----------------| |-----------------|<br>| main.c          | | crtlib.c         |<br>|-----------------| |-----------------|<br>|                 | |                 |<br>|  编译            | |  编译            |<br>|                 | |                 |<br>|-----------------| |-----------------|<br>| main.o          | | crtlib.o         |<br>|-----------------| |-----------------|<br>|                 | |</code>

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