Thread: What kind of syntax is this?

The sample code accompanying a textbook I'm reading (on image analysis) has function definitions in an unusual syntax that I've never seen before. The compiler accepts it with no complaints, but I'm wondering where this syntax comes from. Anybody know anything about its history?

Here's a example (not from the book - just my own simple example to show the syntax):

Code:

#include <stdio.h>

int
main( argc, argv )	//This is the part I find unusual.
	int argc;	//It's sort of nice because provides convenient space to
	char* argv[];	//attach comments about each of the function arguments.
{
	char buffer[100];
	strcpy(buffer, "world");
	if( argc == 2 )
	{
		   strcpy( buffer, argv[1] );
	}
	printf( "Hello, %s\n", &buffer );
	return 0;
}

argc, argv are arguments to main in C (Google!)

though I write it like

Code:

int main(int argc, char* argv[])

Originally Posted by abh!shek

argc, argv are arguments to main in C (Google!)

though I write it like

Code:

int main(int argc, char* argv[])

Duh, of course argc and argv are arguments to main. My point is that I've never seen arguments to a function defined on separate lines outside the argument list. Have you?

That's K&R syntax, which was before ANSI standards.

How old is your book?

I've never seen it before either.
Does it even compile to todays standards?

The book is "Practical Algorithms for Image Analysis" by Michael Seul, Lawrence O'Gorman and Michael J. Sammon first published in 2000.

I don't think it's K&R syntax -- unless it's from K&R's first edition. In my copy of K&R (2nd edition), they say (bottom of pg. 69):

Code:

Each function definition has the form:
return-type function-name( argument declarations)
{
    declarations and statements
}

...in other words, what I think of as "standard" C.

Originally Posted by sand_man

I've never seen it before either.
Does it even compile to todays standards?

GCC 3.3 compiles it with no complaints.
GCC 4.1 compiles it, with a warning:
warning: incompatible implicit declaration of built-in function ‘strcpy’
which obviously has nothing to do with the format of the function name and arguments.

(I forgot to #include <string.h>)

http://cm.bell-labs.com/cm/cs/cbook/

The cover advertises it as ANSI C, although the standard wasn't finalized until a year or so later.

Originally Posted by laserlight

It is still standard in C99 (refer to section 6.9.1 paragraph 13).

Here int a, b; is the declaration list for the parameters. The difference between these two definitions is that the first form acts as a prototype declaration that forces conversion of the arguments of subsequent calls to the function, whereas the second form does not.

Interesting. I didn't know it was legal in ANSI/ISO C, much less there was any difference.