The C Book

C is a remarkable language. Designed originally by one man, Dennis Ritchie, working at AT&T Bell Laboratories in New Jersey, it has increased in use until now it may well be one of the most widely-written computer languages in the world. The success of C is due to a number of factors, none of them key, but all of them important. Perhaps the most significant of all is that C was developed by real practioners of programming and was designed for practical day-to-day use, not for show or for demonstration. Like any well-designed tool, it falls easily to the hand and feels good to use. Instead of providing constraints, checks and rigorous boundaries, it concentrates on providing you with power and on not getting in your way.

Because of this, it’s better for professionals than beginners. In the early stages of learning to program you need a protective environment that gives feedback on mistakes and helps you to get results quickly—programs that run, even if they don’t do what you meant. C is not like that! A professional forester would use a chain-saw to cut down trees quickly, aware of the dangers of touching the blade when the machine is running; C programmers work in a similar way. Although modern C compilers do provide a limited amount of feedback when they notice something that is out of the ordinary, you almost always have the option of forcing the compiler to do what you said you wanted and to stop it from complaining. Provided that what you said you wanted was what you really did want, then you’ll get the result you expected. Programming in C is like eating red meat and drinking strong rum except your arteries and liver are more likely to survive it.

Not only is C popular and a powerful asset in the armoury of the serious day-to-day programmer, there are other reasons for the success of this language. It has always been associated with the UNIX operating system and has benefited from the increasing popularity of that system. Although it is not the obvious first choice for writing large commercial data processing applications, C has the great advantage of always being available on commercial UNIX implementations. UNIX is written in C, so whenever UNIX is implemented on a new type of hardware, getting a C compiler to work for that system is the first task. As a result it is almost impossible to find a UNIX system without support for C, so the software vendors who want to target the UNIX marketplace find that C is the best bet if they want to get wide coverage of the systems available. Realistically, C is the first choice for portability of software in the UNIX environment.

C has also gained substantially in use and availability from the explosive expansion of the Personal Computer market. C could almost have been designed specifically for the development of software for the PC—developers get not only the readability and productivity of a high-level language, but also the power to get the most out of the PC architecture without having to resort to the use of assembly code. C is practically unique in its ability to span two levels of programming; as well as providing high-level control of flow, data structures and procedures—all of the stuff expected in a modern high-level language—it also allows systems programmers to address machine words, manipulate bits and get close to the underlying hardware if they want to. That combination of features is very desirable in the competitive PC software markeplace and an increasing number of software developers have made C their primary language as a result.

Finally, the extensibility of C has contributed in no small way to its popularity. Many other languages have failed to provide the file access and general input-output features that are needed for industrial-strength applications. Traditionally, in these languages I/O is built-in and is actually understood by the compiler. A master-stroke in the design of C (and interestingly, one of the strengths of the UNIX system too) has been to take the view that if you don’t know how to provide a complete solution to a generic requirement, instead of providing half a solution (which invariably pleases nobody), you should allow the users to build their own. Software designers the world over have something to learn from this! It’s the approach that has been taken by C, and not only for I/O. Through the use of library functions you can extend the language in many ways to provide features that the designers didn’t think of. There’s proof of this in the so-called Standard I/O Library (stdio), which matured more slowly than the language, but had become a sort of standard all of its own before the Standard Committee give it official blessing. It proved that it is possible to develop a model of file I/O and associated features that is portable to many more systems than UNIX, which is where it was first wrought. Despite the ability of C to provide access to low-level hardware features, judicious style and the use of the stdio package results in highly portable programs; many of which are to be found running on top of operating systems that look very different from one another. The nice thing about this library is that if you don’t like what it does, but you have the appropriate technical skills, you can usually extend it to do what you do want, or bypass it altogether.