Customer billing system in C Program

Customer billing system

Customer Billing System Project is a simple console application designed to demonstrate the practical use of C programming language and its features as wells as to generate an application which can be used in any departmental store, shops, cafes etc. for billing to the customer.

You can use this application to keep the records such as name, address, mobile number, paid amount, due amount, payment date etc. of your regular costumer. Moreover, if you have a new customer, you can add and edit the account at any time.

The source code of Customer Billing System Project in C has been written in C programming language without of the use of any graphics. The code is complete, totally error free and not that long – just. It is to be compiled in Code::Blocks  using GCC compiler. You can directly download the source code from any of the links provided here.

 #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;
	   }