Customer billing System

SOURCE CODE:

 #include<stdio.h>
 #include<conio.h>
 #include<stdlib.h>

 void input();
 void writefile();
 void search();
 void output();

 struct date{
   int month;
   int day;
   int year;
   };

  struct account {
int number;
char name[100];
int acct_no;
float mobile_no;
char street[100];
char city[100];
char acct_type;
float oldbalance;
float newbalance;
float payment;
struct date lastpayment;
  }customer;
  int tl,sl,ts;
 void main()
{
  int i,n;
  char ch;
  clrscr();

  _setcursortype(_NOCURSOR);
  printf("   CUSTOMER BILLING SYSTEM:\n\n");
  printf("===============================\n");
  printf("\n1:    to add account on list\n");
  printf("2:    to search customer account\n");
  printf("3:    exit\n");
  printf("\n================================\n");
  do{
       printf("\nselect what do you want to do?");
       ch=getche();
  }while(ch<='0' || ch>'3');
  switch(ch){
case '1':
clrscr();
printf("\nhow many customer accounts?");
scanf("%d",&n);
for(i=0;i<n;i++){
input();
if(customer.payment>0)
customer.acct_type=(customer.payment<0.1*customer.oldbalance)? 'O': 'D';
else
customer.acct_type=(customer.oldbalance>0)?'D' : 'C';

customer.newbalance=customer.oldbalance - customer.payment;
writefile();
}
main();
case '2':
clrscr();
printf("search by what?\n");
printf("\n1 --- search by customer number\n");
printf("2 --- search by customer name\n");
search();
ch=getche();
main();
case '3':
clrscr();
delay(700);
textcolor(RED);
gotoxy(25,25);
cprintf("\nA PROJECT BY BIDUR & SUJAN");
delay(1500);
exit(1);
  }
 }


   void input()
{
  FILE *fp=fopen("bidur.dat","rb");
  fseek (fp,0,SEEK_END);
  tl=ftell(fp);
  sl=sizeof(customer);
  ts=tl/sl;
  fseek(fp,(ts-1)*sl,SEEK_SET);
  fread(&customer,sizeof(customer),1,fp);
  printf("\ncustomer no:%d\n",++customer.number);
  fclose(fp);
  printf("         Account number:");
  scanf("%d",&customer.acct_no);
  printf("\n       Name:");
  scanf("%s",customer.name);
  printf("\n       mobile no:");
  scanf("%f",&customer.mobile_no);
  printf("         Street:");
  scanf("%s",customer.street);
  printf("         City:");
  scanf("%s",customer.city);
  printf("         Previous balance:");
  scanf("%f",&customer.oldbalance);
  printf("         Current payment:");
  scanf("%f",&customer.payment);
  printf("         Payment date(mm/dd/yyyy):");
  scanf("%d/%d/%d",&customer.lastpayment.month,&customer.lastpayment.day,&customer.lastpayment.year);
  return;
   }

   void writefile()
   {
  FILE *fp;
  fp=fopen("bidur.dat","ab");
  fwrite(&customer,sizeof(customer),1,fp);
  fclose(fp);
  return;
   }

   void search()
   {
char ch;
char nam[100];
int n,i,m=1;
FILE *fp;
fp=fopen("bidur.dat","rb");
do{
printf("\nenter your choice:");
ch=getche();
}while(ch!='1' && ch!='2');
switch(ch){
      case '1':
    fseek(fp,0,SEEK_END);
    tl=ftell(fp);
    sl=sizeof(customer);
    ts=tl/sl;
    do{
printf("\nchoose customer number:");
scanf("%d",&n);
if(n<=0 || n>ts)
printf("\nenter correct\n");
else{
    fseek(fp,(n-1)*sl,SEEK_SET);
    fread(&customer,sl,1,fp);
    output();
}
printf("\n\nagain?(y/n)");
ch=getche();
    }while(ch=='y');
    fclose(fp);
    break;
      case '2':
    fseek(fp,0,SEEK_END);
    tl=ftell(fp);
    sl=sizeof(customer);
    ts=tl/sl;
    fseek(fp,(ts-1)*sl,SEEK_SET);
    fread(&customer,sizeof(customer),1,fp);
    n=customer.number;

    do{
printf("\nenter the name:");
scanf("%s",nam);
fseek(fp,0,SEEK_SET);
for(i=1;i<=n;i++)
{
     fread(&customer,sizeof(customer),1,fp);
     if(strcmp(customer.name,nam)==0)
     {
output();
m=0;
break;
     }
}
if(m!=0)
printf("\n\ndoesn't exist\n");
printf("\nanother?(y/n)");
ch=getche();
    }while(ch=='y');
    fclose(fp);
      }
      return;
}



   void output()
{
   printf("\n\n    Customer no    :%d\n",customer.number);
   printf("    Name    :%s\n",customer.name);
   printf("    Mobile no      :%.f\n",customer.mobile_no);
   printf("    Account number :%d\n",customer.acct_no);
   printf("    Street         :%s\n",customer.street);
   printf("    City           :%s\n",customer.city);
   printf("    Old balance    :%.2f\n",customer.oldbalance);
   printf("    Current payment:%.2f\n",customer.payment);
   printf("    New balance    :%.2f\n",customer.newbalance);
   printf("    Payment date   :%d/%d/%d\n\n",customer.lastpayment.month,customer.lastpayment.day,customer.lastpayment.year);
   printf("    Account status :");
   textcolor(128+RED);
   switch(customer.acct_type)
      {
      case 'C':
cprintf("CURRENT\n\n");
break;
      case 'O':
cprintf("OVERDUE\n\n");
break;
      case 'D':
cprintf("DELINQUENT\n\n");
break;
      default:
cprintf("ERROR\\n\n");
      }
      textcolor(WHITE);
      return;
   }