What is Portability in C Programming?

Answer: Linux is a portable operating system which supports wide range of computer architectures. Portability refers to how easily- if at all- code can move from one system architecture to another. We know that Linux is a portable because it has already been ported to various implementations. To view which implementations Linux has ported to, type in the following command

vim /usr/src/kernels/2.6.43.8-1.fc15.x86_64/arch/

and output views as

alpha/     c6x/     hexagon/ m68k/       openrisc/ score/   um/
arm/       cris/    ia64/    microblaze/ parisc/   sh/      unicore32/
avr32/     frv/     Kconfig  mips/       powerpc/  sparc/   x86/
blackfin/  h8300/   m32r/    mn10300/    s390/     tile/    xtensa/

Portability of a C program across the wide range of implementations requires to use standard library which has mandated set of functions and they will have the required interface and then work in the the prescribed manner.

ANSI C implementations include library in specification. Further, ANSI implementations aren’t prohibited from adding additional functions in the library. But if you are concerned with writing portable code use standard functions and avoid any non-standard functions.