How to open a .a file

Question

I've a little problem: I have to open a linker file that has .a extension. I use Dev-C++.

Tearoom

Hello Ale, can you show us what have you come up with so far? – Tiffaneytiffani

@Mgst: What are you trying to achieve? – Tiffaneytiffani

Answer 1

.a files are ar archives (something like zip archives) of object (.o) files. You can list files in .a file using ar program:

ar t file.a

And extract all files:

ar x file.a

Winn

Answer 2

Files with the .a extension are static libraries using Unix file naming conventions. They're not much more than an indexed collection of object code. You don't so much open them (unless you've got a tool like nm or gdb available, both of which can do sensible things with a library if not necessarily what you might want) as tell the linker to use them when linking. With most linkers, it's important to put all libraries (both static and dynamic/shared) after your main program code on the linker command line and the order of libraries matters too.

Beggarly

Answer 3

Do you really mean that you want to open the file, or rather that you wish to link it with your code?

Dev-C++ by default is installed with the MinGW/GCC compiler. If the archive is not specifically built to work with MinGW (for example it may be a Cygwin or Linux archive), you will not be able to link it to MinGW generated code.

If the archive is a MinGW/GCC compatible library, then you simply link it to your code. In Dev-C++ you need to add the archive to the project linker options, either by adding the full path to the archive (there's a button for that in the project options), or by placing the archive in a path defined by a -L<path> option, and then adding a -l<archive> option. Note that id the archive is called libXXX.a, then the -l<archive> option will be `-lXXX'; the "lib" prefix and ".a" extension are implicit.

If you simply want to inspect an archive to determine what external symbols it provides, then the nm utility can be used for that. If you want to extract the individual object files, then use the ar, though I cannot think of a good reason why you'd want to do either.

Pennon

Answer 4

Try fstream, or fstream file_op("c:\\test.a",ios::in);, and dont forget to include fstream.h.

Tiffaneytiffani

That is perhaps what he asked for, but most probably not what he actually wanted. – Pennon

@Pennon But it's the problem o the question, but not the answer. So why -1? – Madewell

@Draco Ater: I didn't vote it down it (your assumption). Sometimes a question may be asked without sufficient technical knowledge or correct terminology to express it clearly, and I suspect that this is such a situation. Occam's Razor should be applied; ask yourself "Why would someone (especially a novice) wish to open an archive as opposed to just use it in the normal manner by linking it?". Moreover, he mentioned the IDE in use, which suggests he needs to know how to use the library in the IDE not in code. Read the comments and answers from others to see why this may not be the answer. – Pennon