Thread: Question on C syntax

hi,
I came across this code online on a tutorial site. This part of the code confused me.

Code:

/*
 * parse--split the command in buf into
 *         individual arguments.
 */
parse(buf, args)
char *buf;
char **args;
{
    while (*buf != NULL) {
        /*
         * Strip whitespace.  Use nulls, so
         * that the previous argument is terminated
         * automatically.
         */
        while ((*buf == ' ') || (*buf == '\t'))
            *buf++ = NULL;

        /*
         * Save the argument.
         */
        *args++ = buf;

        /*
         * Skip over the argument.
         */
        while ((*buf != NULL) && (*buf != ' ') && (*buf != '\t'))
            buf++;
    }

    *args = NULL;
}

What confused me was the local variables declared ouside the opening brace of the function definition. I have also seen such code before once but thought it was a typo. But obviously this is a valid syntax. Can someone clear this for me please.

-Livin

Salem is correct. Depending on the material you're reading, you may see them more often than you might have expected. Anyway, it's really just the old way to define a function:

Code:

parse(buf, args)
char *buf;
char **args;
{
    /* code here */
}

is the same as

Code:

int parse (char *buf, char **args)
{
    /* code here */
}

If you don't see a return type, it is automatically int. That's really the only nuance of the syntax that could make it difficult to understand in my opinion.

This may be obvious, but you do not want to use the K&R style functions in new code. K&R declarations are not prototypes, so the compiler cannot check to make sure you're calling a function properly. If you try to provide a prototype for a K&R style function, problems will occur with certain types (_Bool, char, short, and float) due to promotion issues.

In short, knowing K&R style is good for reading old code, but it should never be used in new code.

Thank you all. I was almost convinced I had some basic concepts missing. Now it makes sense.