Cant Understand the syntax

I've seen the following in a .c File

Code:

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static void MDString PROTO_LIST ((char *));
static void MDTimeTrial PROTO_LIST ((void));
static void MDTestSuite PROTO_LIST ((void));
static void MDFile PROTO_LIST ((char *));
static void MDFilter PROTO_LIST ((void));
static void MDPrint PROTO_LIST ((unsigned char [16]));

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But cant understand what does it mean.
PROTO_LIST is a function or a struct name.
But still the syntax is complex to me I cant understand it.
anyone plese clearify.

Back in the bad old days, C didn't have prototypes, so function declarations looked like:

Code:

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char *f();

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instead of

Code:

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char *f(const char *);

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Or whatever the parameters were. The point is that K&R C (the older dialect) had no way of listing the types of parameters to a function. As you are probably aware, having the types is extremely useful. So people wanted to use prototypes, but also needed to be compatible with older compilers.

Thus you get a macro like PROTO_LIST. Its definition probably looks something like:

Code:

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#if __STDC__
#define PROTO_LIST(p) p
#else
#define PROTO_LIST(p) ()
#endif

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So if __STDC__ is true (that is, we're on a standards-compliant implementation), the prototype is used. If it's false, no prototype is used. Compatible with both ancient and modern compilers.

Haaaaaaaaa I got a Brand knew drop of historical Knowledge.
C didn't have prototypes
Then how did programmers pass the arguments ?

You just passed them. We're talking prototypes, not types.

I meant if Its char *f();
then how can one pass argument to f() ?

You could pass anything you liked (which was part of the problem, and why tools like lint existed).

f(123);
f("hello world");
would silently compile on very old compilers.

so how the function body get that argument.
e.g. now a days we do f(int x)
so if f(123) is used x = 123 but if its f() then who will hold that 123 ??

You would define a function in some manner like this:

Code:

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int dosomething(x)
int x;
{
    printf("x = %d\n", x);
}

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