Question

Recently I’ve been looking at the some of the C example code from the online resources of Steven Skiena’s “Algorithm Design Manual” and have been baffled by the syntax of some of his function calls. Admittedly it’s been a while since did C at uni but I’ve never encountered untyped function arguments like this:

find_path(start,end,parents)
int start;
int end;
int parents[];
{
    if ((start == end) || (end == -1))
        printf("\n%d",start);
    else {
        find_path(starts,parents[end],parents);
        printf(" %d",end);
    }
}

Is this valid syntax anymore? Are / were there any benefits with this style of function declaration? It seems more verbose than the conventional inline typing of arguments.

Answer 1

They are called K&R style definitions. Don’t use them in new code. Even K and R recommend that you stay away from them in “The C Programming Language 2ed”.

A note of history: the biggest change between ANSI C and earlier
versions is how functions are declared and defined.

The parameters are named between the parentheses, and their types are
declared before opening the left brace; undeclared parameters are
taken as int.

The new syntax of function prototypes makes it much easier for a
compiler to detect errors in the number of arguments or their types.
The old style of declaration and definition still works in ANSI C, at
least for a transition period, but we strongly recommend that you use
the new form when you have a compiler that supports it.