Page 426 - C++

#include<conio.h> //header files include
#include<stdlib.h>
#include<stdio.h>
#include<fstream.h>
#include<string.h>
#include<dos.h>
#include<graphics.h>
#include<math.h>
#include<ctype.h>

void add_contact(); //contact functions
void delete_contact();
void modify_contact();

void q_telephone(); //query func
void q_mob();
void q_name();
void q_add();
void q_company();

void sch_add(); //schedule func
void sch_delete();
void sch_modify();
void sch_view();

void front(); //display
int menu();
void back();
void end();

void cal_display(); //calculator
void in();
void out(char*a);
void push(char);
char pop();
void infix_to_postfix(char*b);
long int isOperator(long, long, char);

int top=-1;
char Stack[100]={NULL};
void push(char);
char pop();
void infix_to_postfix(char *);
/*********************************************************/

struct Date
{
int dd, mm, yy;
int hr, min,sec;
};
/*********************************************************/
class Contact
{
char Telephone[9],Mobile1[15],Mobile2[15],email[30];