Semester 02 (Spring 2016) Instructor: Ms. Fasiha /Ms. Sumeera Lab Engineer: Mr. M. Talha/Mr.TMarouf
Lab 11: I/O stream File handling
Objective(s) : Upon completion of this lab session, learners will be able to: 1. Able to read from a file
2. Able to write in a file
Streams
As we have learned in previous lectures that input/output in C++ is based on Streams. A stream is an object that enables the flow of data between a program and some I/O device or file
– If the data flows into a program, then the stream is called an input stream
– If the data flows out of a program, then the stream is called an output stream
In C++ we have two types of streams.
File Streams : Standard streams enable to flow of data between a program to Files stored on secondary storage of computer. File streams are created, connected to files, and disconnected from files by the programmer.
To use file streams, we need to create stream variables and to associate those stream variables to a file. There are certain steps every programming must follow.
Creating file streams
1. First define stream objects
ifstream [stream variable name]; // to read from file ofstream [stream variable name]; // to write in file
fstream [stream variable name]; // for both (reading and writing)
2. Connecting file streams.
Open ()
3. Disconnecting file streams
Close ()
Important File Functions
Input related functions
ifstream fsin;
fsIn.open(const char[] fname)
connects stream fsIn to the external file fname.
fsIn.get(char& character)
extracts next character from the input stream fsIn and places it in the character variable character.
tests for the end-of-file condition.
Output related functions
ofstream fsOut;
fsOut.open(const char[] fname)
connects stream fsOut to the external file fname.
fsOut.put(char character)
inserts character character to the output stream fsOut.
fsOut.eof()
tests for the end-of-file condition.
File Open Modes (Flags)
Name
Description
ios::in
Open file to read
ios::out
Open file to write
ios::app
All the data you write, is put at the end of the file.
It calls ios::out
ios::ate
All the data you write, is put at the end of the file. It does not
call ios::out
ios::trunc
Deletes all previous content in the file. (empties the file)
ios::nocreate
If the file does not exists, opening it with the open() function
gets impossible.
ios::noreplace If the file exists, trying to open it with the open() function,
returns an error.
Example – Reading from a File
# Output 10 30 50 60 20 40 60 80 30 50 70 90 40 60 80 100 50 70 90 110 60 80 100 120
10 30 50 6050 70 90 1100
Example – Writing to a File
EXERCISES
Exercise 1
Write a C++ that perfrom following task:
Create a function Student() that prompt user to a student record. Student contains following details.
ID, Full Name, Email, Department and Phone Number.
Store the input in file student.txt
In main program call function Student()
Program should prompt user that you want to enter a new record. If ‘Y’ ask user for new details. If ‘N’, program should terminate. (Use event controlled loop)
#Sample Output Enter new record:
---Full Name: Sarmad Soomro
ID: 11734
Email: [email protected] Department: Computer Science Phone Number: 090078601
Do you want to enter new record(Y/N)? ___
Exercise 2
Refer to you Exercise 2.
Exercise 3
Refere to you exercise 1 and 2.
Read the data from file student.txt (line by line) and print on you computer screen as follows:
#Sample Output
Student Records Saved:
Sarmad Soomro 11743 [email protected] Computer Science 090078601 Majid Ilim 11603 [email protected] Managment Sciences 090078601 Asim Rizvi 11700 [email protected] Computer Science 090078601
Exercise 4
Write a C++ program that compute Net Salary of Employee. Program contains two user defined functions empSalary() and display().
Create a structure of Employee that contains following data members:
o EmployeeNumber, Name, BasicSalary, HouseAllowence, MedicalAllowence,Tax, GrossPay and NetSalary
empSalary() compute salary with given criteria Salary will be computer on following criteria
o HouseAllowence = 10% of BasicSalary
o Medical Allowence = 5% of Basic Salary
o Tax = 4 % of Basic Salary
o GrossSalary = Basic+HouseAllowence+MedicalAllowence
o NetSalary = GrossSalary – Tax
Exercise 5
Write a C++ program for billing system of MovInPeak restaurant. The program should perform following tasks:
Show menu to customer for orders.
Allow the customer to select more than one item from the menu.
Calculate and print the bill.
Assume that the restaurant offers the following items (the price of each item is shown to the right of the item):
Omlet $1.45
French Omlet $2.45
Muffin $0.99
French Toast $1.99
Fruit Basket $2.49
Cereal $0.69
Coffee $0.75
Tea $0.50
Notes:
Store these prices in a file price.txt by using notepad. (No need to do in DevC++)
Your program must contain following functions:
o Function showMenu: This function shows the different items offered by the restaurant and tells the user how to select the items. Read the items from file price.txt and display to user.
o Function printCheck: This function calculates, print the receipt to user and also store record in a file moveinpeak.txt.
#Sample Output
Welcome to MovinPeak Restaurant
What do you want to order. Please enter quantity of each item: Item –--- Price
----Omlet $1.45 : 0
French Omlet $2.45 : 1
Muffin $0.99 : 1
French Toast $1.99 : 0 Fruit Basket $2.49 : 0 Cereal $0.69 : 0 Coffee $0.75 : 1 Tea $0.50 : 0 ************************
Bill
************************ French Omlel $2.45
Muffin $0.99
Coffee $0.75
Tax $0.20
************************ Amount Due $4.39
************************
