int sw(argc,argv,let,val)
int argc;
char *argv[];
char *let;
long int *val;
{
/*
	this subroutine parses switches on the command line.
	switches are of the form -<letter><value>.  If one is
	found, a pointer to the letter is returned in let 
	and a pointer to the value in val as a long integer. 


	parameters argc and argv are passed in from the main
	calling program.
	Note that if argc = 1 then only the command is left and
	the line is empty.
	if a switch is decoded, the value of the function is 1
	otherwise it is zero.
	
	a number following the letter is decoded as
	a decimal value unless it has a leading x in which case
	it is decoded as hexadecimal.

*/
	long int atol();
	int sscanf();
/*
	either nothing is left or what is left is not
	a switch
*/
	if( (argc == 1)  ||  (*argv[1] != '-') )
	  {
	  *let='\0';
	  *val=0;
	  return(0);
	}
	*let= *++argv[1];   /*get the letter after the - character*/
	if( *++argv[1]  != 'x')   /*if next char is not x, decode number*/
	  *val=atol(argv[1]);
	else
	  {
	  argv[1]++;    /*skip over x and decode value in hex */
	  sscanf(argv[1]," %lx ",val);
	}
	return(1);
}