The difference between static library and dynamic library of program

Functions are code blocks that can be reused throughout the program . Using them can save time , No need to rewrite the code many times . Same as function , Libraries can also save time , Because they enable functions to be reused in multiple programs .

​ A static library or static link library is a set of routines , External functions and variables , They are parsed in the caller at compile time , And by the compiler , The linker or binder is copied to the target application , Thus, the object file and an independent executable file are generated . Dynamic links only include the address of the Library （ Static links are a waste of space ） Dynamic links link libraries at runtime .

Although static libraries can be reused in multiple programs , But it will be locked into the program at compile time . On the other hand , Dynamic or shared libraries exist as separate files from executable files .
The disadvantage of using a static library is that its code is locked into the final executable , It cannot be modified without recompiling . contrary , Dynamic libraries can be modified without recompiling .
Because the dynamic library is outside the executable , Therefore, the program only needs to make a copy of the library file at compile time . Using a static library means that every file in the program must have its own copy of the library file at compile time .
The disadvantage of using dynamic libraries is that programs are easier to break . for example , If the dynamic library is damaged , Then the executable may no longer work . however , Static libraries are inaccessible , Because it exists in the executable .
The benefits of using dynamic libraries are , Multiple running applications can use the same library , Instead of requiring each application to have its own copy .
Another advantage of using static libraries is the execution speed of the runtime . Because its object code （ Binary system ） Already included in the executable , So calls to multiple functions can be processed faster than dynamic library code , The code of the dynamic library needs to be called from a file other than the executable .
When to use them ？

​ If you have many documents , Multiple copies of the static library mean that the size of the executable file increases , Then it is recommended to use dynamic library , Can save time . If the benefits of execution time outweigh the need to save space , Then static library is the best choice .