Static library

In

static memory offset

determined at compile-time/link-time.

Advantages and disadvantages

There are several advantages to statically linking libraries with an executable instead of

dynamically linking them. The most significant advantage is that the application can be certain that all its libraries are present and that they are the correct version. This avoids dependency problems, known colloquially as DLL Hell or more generally dependency hell

. Static linking can also allow the application to be contained in a single executable file, simplifying distribution and installation.

With static linking, it is enough to include those parts of the library that are directly and indirectly referenced by the target executable (or target library). With dynamic libraries, the entire library is loaded, as it is not known in advance which functions will be invoked by applications. Whether this advantage is significant in practice depends on the structure of the library.

In static linking, the size of the executable becomes greater than in dynamic linking, as the library code is stored within the executable rather than in separate files. But if library files are counted as part of the application then the total size will be similar, or even smaller if the compiler eliminates the unused symbols.

Environment specific

On

package management systems

can be used to ensure the correct library files are available. This allows the library files to be shared between many applications leading to space savings. It also allows the library to be updated to fix bugs and security flaws without updating the applications that use the library. In practice, many executables (especially those targeting Microsoft Windows) use both static and dynamic libraries.

Linking and loading

Any static library function can call a function or procedure in another static library. The

linking loader (e.g., the X11

module loader). However, whether such a process can be called static linking is controversial.

Creating static libraries in C/C++

Static libraries can be easily created in

external linkage (i.e. by not using the C static keyword). Static library filenames usually have ".a" extension on Unix-like systems^[1] and ".lib" extension on Microsoft Windows

.

For example, on a Unix-like system, to create an archive named libclass.a from files class1.o, class2.o, class3.o, the following command would be used:[1]

ar rcs libclass.a class1.o class2.o class3.o

to compile a program that depends on class1.o, class2.o, and class3.o, one could do:

cc main.c libclass.a

or (if libclass.a is placed in standard library path, like /usr/local/lib)

cc main.c -lclass

or (during linking)

ld ... main.o -lclass ...

instead of:

cc main.c class1.o class2.o class3.o

References

^ ^a ^b ^c "Static Libraries". TLDP. Retrieved 3 October 2013.
^ Anderson, Rick (2000-01-11). "The End of DLL Hell". microsoft.com. Archived from the original on 2001-06-05. Retrieved 2013-08-31. Private DLLs are DLLs that are installed with a specific application and used only by that application.

[Static_Libraries-1] "Static Libraries". TLDP. Retrieved 3 October 2013.

[endofdllhell-2] Anderson, Rick (2000-01-11). "The End of DLL Hell". microsoft.com. Archived from the original on 2001-06-05. Retrieved 2013-08-31. Private DLLs are DLLs that are installed with a specific application and used only by that application.

[1]

v t e Application binary interface (ABI)
Parts and conventions	Alignment Calling convention Call stack Library static Machine code Memory segmentation Name mangling Object code Opaque pointer Position-independent code Relocation System call Virtual method table
Related topics	Binary-code compatibility Foreign function interface Language binding Linker dynamic Loader Year 2038 problem

Advantages and disadvantages

Environment specific

Linking and loading

Creating static libraries in C/C++

See also

References