#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <string.h>
 
#define COMPANY "Rocklin Realty"
#define TRUE	1
#define TAB		25
 
void setagents(double *a, int c);
void total_sales(double *m, char **cal, int c);
void agent_sales(double *m, char **cal, int c);
void valid_date(char *date, int min_yr, int max_yr);
void titles(void);
int headings(void);
int menu(void);
void add(void);
int quit(void);
void message(char *msg);
int menuvalid(int min, int max, char item[]);
 
 
char *names[] = {"Larry Lister", "Sue Sales", "Eva Escrow", "Morley Money", "Pete Profit" };
 
 
 
typedef struct
	{
	char aname[15], date[9];
	int acode;
	double price;
	} REALTOR;
 
 
#define clrscr() system("cls")
 
int main()
	{
 
	int key, more = TRUE;
	do
		{
		key = menu();
		switch (key)
			{
			case 1: add();		break;
			case 2: total_sales(); break;
			case 3: agent_sales(); break; 
			case 4: more = quit(); break;
			default: message("\nError in selection\a");
			}
		}
		while (more);
		return 0;
	}
/*  ================================================================  */
int menu()
	{
	int choice;
	titles();
	printf("1 = Add Records\n", TAB, ' ');
	printf("2 = Report Total Sales\n", TAB, ' ');
	printf("3 = Report Agent Sales\n", TAB, ' ');
	printf("\4 = Quit\n", TAB, ' ');
 
	choice = menuvalid(1, 4, "choice");
	return(choice);
	}
/*  ================================================================  */
/**/
void add()
	{
	double agents[6];
	double price;
	int aname, c, more, items, key;
	char choice;
	REALTOR s;
	FILE *fp;
 
 
	fp = fopen("sales.dat", "w+b");
	if (fp == NULL)
		{
		message("Error opening sales.dat\a");
		return;
		}
	fseek(fp, 0L, SEEK_END);
	c = (int)ftell(fp) / sizeof(s);
	setagents(agents,6);
	do
		{
		printf("Enter an agent code (1-5): ");
		scanf("%d%*c", s.aname);
		printf("Enter sale date for %s: ", names[aname-1]);
		gets(s.date);
		printf("Enter the sale price : ");
		scanf("%lf%*c", s.price);
 
		}
/*  ================================================================  */
void titles()
{
  clrscr();
  printf("%*c %s\n\n", TAB, ' ',COMPANY);
 
/*  ================================================================  */
void message(char *msg)
{
printf("%s, press Enter key to continue\n", msg);
getchar();
}
 
/*  ================================================================  */
int quit()
{
   int c, more = TRUE;
c = prompt("\nTerminate program");
if (c == 'Y')
   {
   clrscr();
   message("\nRocklin Realty Sales Database terminated successfully");
   more = FALSE;
   }
return more;
}
 
/*  ================================================================  */
 
  void valid_date(char *date, int min_yr, int max_yr)
{
   int  mm, dd, yy, max_dd, good;
   char msg[80];
do
   {
   printf("Enter the date (mm/dd/yy), press RETURN to quit: ");
   gets(date);
   if (!date[0]) return;
   good = parsedate(date, &mm, &dd, &yy);
   if (!good)
      {
      message("Date must be in mm/dd/yy format\a");
      continue;
      }
   if (yy < min_yr || yy > max_yr)
      {
      sprintf(msg, "Year out of range %d to %d\a", min_yr, max_yr);
      message(msg);
      good = FALSE;
      continue;
      }
   if (mm < 1 || mm > 12)
      {
      message("Month out of range\a");
      good = FALSE;
      continue;
      }
   if (mm==4 || mm==6 || mm==9 || mm==11) max_dd = 30;
   else if (mm==2)
						{
						if (ISLEAP(1900+yy)) max_dd = 29;
						else max_dd = 28;
						}
				else max_dd = 31;
	 if (dd < 1 || dd > max_dd)
      {
      message("Day out of range\a");
      good = FALSE;
      continue;
      }
   }
while (!good);
}
/*  ================================================================  */
 
int menuvalid(int min, int max, char item[])
{
   int n;
   char buffer[80];
printf("Enter the %s %d to %d: ", item, min, max);
gets(buffer);
n = atoi(buffer);
while (n < min || n > max)
   {
   message("\nRange Error\a");
   printf("Enter the %s %d to %d: ", item, min, max);
   gets(buffer);
   n = atoi(buffer);
   }
return(n);
}
/*  ================================================================  */

Error 1: error C2660: 'total_sales' : function does not take 0 arguments

void total_sales(double *m, char **cal, int c);

case 2: total_sales(double *m, char **cal, int c); break;

int sun( int a, int b);

sum(1, 2);
 
or 
 
int a = 10;
int b = 20;
 
sum(a, b);