how to make your own library in C++ ?

Question

i want to use my own functions in my own library which can be included in other programs,how do u make a library e.g mylibrary.h in c++?

Answer 1

1) Create the files "mylibrary.h" and "mylibrary.cpp".

2) Only compile the library, and it shouldn't have a "main()" function in it. This step will generate an object file called "myfile.o".

3) Create another file called something like "main.cpp". In main.cpp you need to #include "mylibrary.h".

4) Compile main.cpp and add the library from step 2 to link in (in this case "myfile.o"). If you don't add this library, you'll get a error message like "linker error - can't find function definition", or something like that.

Answer 2

Aerivium is correct as far as he goes. Obviously the first thing he mentioned -- you want to compile but not link your routines. Why not? Because you'll be linking them in with the other libraries. In fact, in gcc in linux which I use, you compile them with a command line like:

g++ -o myprogram.o -c myprogram.cc and then use ar as in ar mylib.a myprog.o. That is a static library which will be compiled into the final code. For a dynamic library -- sorry, I haven't done that.



Turbo C used to compile to object files (.obj) when I used them. Those are the same as .o files and you can link them into libraries.



If I were you, I would read the documentation on your compiler carefully.



Here are a couple of tutorials using versions of C I don't know much about.



http://www.hlrs.de/organization/tsc/services/tools/docu/kcc/tutorials/libraries.html



http://docs.sun.com/source/819-3690/Building.Libs.html



http://www.openismus.com/documents/linux/building_libraries/building_libraries.shtml

Answer 3

Under Linux:



use the ar command to create your archive(lib), e.g.,



$ g++ -c test1.c create test1.o



$ g++ -c test2.c create test2.o



Now add the object files to the archive

$ ar cr libmydemo.a test2.o test1.o





Next step is to compile and link it:



$ g++ -o test3 test3.c -L. -lmydemo



Here, "-L." is used to tell the system that when the compiler searches for library files it should also include the current directory. The name of the library is passed using the -l command option, you call the library without the lib prefix and the .a extension..

Answer 4

Library isn't some thing yet .c/.cpp archives with header archives. case in point, you've the want to make a maths library: Create following archives: maths.h: placed all function declarations, or in C++, placed type declarations in straight forward words maths.c/.cpp: placed all definitions right here Thats it, your library is waiting. to apply it, only contain its .h report on your application, and link .cpp report. Gorav

Answer 5

make files called mylibrary.h and mylibrary.c



mylibrary.h just has prototype methods with no bodies



eg: void doSomeStuff(int* stuff);



mylibrary.c has all of these functions again but with their bodies



eg: void doSomeStuff(int* stuff){

printf("%i",stuff);

}



you then include the .h file when you want to use it



once you've compiled it once you will get a mylibrary.o, this and the .h file are all you need to use it, the .c is only needed to change it and recompile the .o file