Thread: function library (from scratch)?

The easiest of these to start trying to duplicate will be something like ctype.h. Look and see what functions it has, and then try to make them on your own. The stdio.h and stdlib.h functions are going to be harder than making say string.h. I used to have a book that covered making your own standard library, but I guess I gave it away.


Quzah.

The first step would be to decide what type of library you want to create.

The basic question of what you expect the library to achieve is important. If you are seeking to give an alternative to standard library functions, you need to specify what makes yours better - particularly if you want other people to use your library.

There is actually no such thing as "from scratch". Any library you write will rely on some understanding or assumptions about the target system (eg what services the system provides that you can rely on - even if that is a set of machine registers and assembler instructions) and how functions in the library will be used. If you are doing file I/O, for example, you are relying on some services from the host system.

There is also the question of portability: if you are not using the standard library, and care about your library being usable across operating systems, compilers, etc then you need to define a workable API (eg a set of function signatures) and also worry about concerns of porting the library to multiple systems. If you are not using the standard library, then the likelihood of your library requiring different implementations for different systems will increase.

A practical concern - for any library you want someone else to use - is whether you intend to distribute your library as source code or as compiled binaries. If you distribute as source code, you allow users of the library to make changes if they need to (to port it, to enhance it). That means you need to manage the potential of getting bug reports for versions of your library that someone else has changed. If you distribute as binary (compiled form) you need to be clear about what systems and compilers you support, ensure your verification and testing works on all those systems (and is applied), ensure porting to new platforms is handled in a timely manner, etc etc.

Originally Posted by SirJiub

but what i don't get is how you're going to define those functions to DO anything if you don't already have any functions to work with.

You have to write the functions. I thought that's what you said you wanted to do? There's a reason I suggested starting with ctype instead of say... stdio. It has the easiest class of functions for you to try to make on your own.


Quzah.