[c] passing a pointer to pointer to a function (i think)

...
main (int argc, char *argv[])
{
	...
	...
	while (--argc > 0 && (*++argv)[0] == '-')
		while (c = *++argv[0])
			...
			...

#include <stdio.h>

void test(int *argc, char **argv)
{
	int c;
	
	printf("function call   ");
	
	(*argc)--;	/* knock the value of argc down 1 (to know when end in main) */
	argv++;		/* intended to step to the next string */
	while(c = *argv++[0])	/* intended to step through chars of string */
		putchar(c);
	
	putchar('\n');
}

main (int argc, char **argv)
{
	while(argc > 0)		/* not call function if no more strings in argv */
		test(&argc, **argv);
}

#include <stdio.h>

void test(int *argc, char **argv)
{
	char c;
	
	(*argc)--;	/* knock argc down 1 to know when to stop in main */
	argv++;		/* step to the next string */
	
	printf("%d: ", *argc);
	
	while(c = *argv[0]++)	/* step through chars in the string */
		putchar(c);
		
	putchar('\n');
}

main (int argc, char **argv)
{
	while(argc > 1)		/* not call function if no more strings in argv */
		test(&argc, argv);
}

command line - ./a.out abc de fghi

                 argv
                  /
                 /
          ______/__________________________________
          | argv[0] | argv[1] | argv[2] | argv[3] |
          -----------------------------------------
          /            /          |          |
  _______/___    _____/___     ___|__    ____|____
  | ./a.out |    |  abc  |     | de |    | fghi  |
  -----------    ---------     ------    ---------

In test() you are incrementing test's copy of argv so that argv now
points to argv[1].  You then go through your loop that increments the
value in argv[1] to point to each character successively until you
reach the '\0'.  When your loop is finished argv[1] points to the character
just past the '\0'.  The value in argv[1] that you have been changing is
the value in the original argv[1] since that is the copy that argv points
to.  You then call test() again and once again you use the value in argv[1]
to traverse the string.  argv[1] points to the character just past the '\0'
from the last call to test().  This just happens to be the next parameter.
If you look at the values of argv[1] and argv[2] after the first call to
test() you will see that they are the same.  You continue with this process
until you have processed all of the parameters.  I think the part that you
are missing is that you never actually traverse the list of parameters.  If
the program loader actually placed the parameters in non-adjacent memory
locations you would see that your code would only correctly print out the
first one.