Re: Code critique: checking for syntax errors

[Jesse Ruffin <jesse@ajp-services.net>]

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James Colannino wrote:
| Do stricter and older compilers complain if variables aren't declared at
| the beginning of the function?
| Actually, I was banking on the C99 standard (I guess perhaps it would
| have been wise for me to say so when I posted the code.)

If you are using a C99 compiler it won't, but older C specifications do
not allow variable definition anywhere but the beginning or between the
function declaration and definition (K&R style). Although C99 is gaining
a lot of ground, I believe that there still are some compilers that
don't support it at all, and many that don't by default.

| I can understand EXIT_FAILURE, but why do all the C books tell you to
| return 0 instead of EXIT_SUCCESS?  I always thought that both return()
| and exit() did the same basic thing, so I'm confused as to why a book
| teaching how to write portable code would say to simply use 0 (that's
| with return() and not exit().)  I have implemented exit(EXIT_FAILURE)
| instead of exit(1).

The man page for exit has this to say about EXIT_*:

| The  use of EXIT_SUCCESS and EXIT_FAILURE is slightly more portable (to
| non-Unix environments) than that of 0 and some non-zero value like 1 or
| -1. In particular, VMS uses a different convention.

and the info pages on exit vs. return:

| A process terminates normally when its program signals it is done by
| calling `exit'.  Returning from `main' is equivalent to calling `exit',
| and the value that `main' returns is used as the argument to `exit'.

Hope that helps a bit.
Also, #defines are almost always better than hard coded values. If
nothing else they're more readable, and often centralize changes.

Jesse Ruffin
AJP Services
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