As we examine files, explain how Input/Output data files work in a program, and how you would use a loop to process input and/or output. Define the differences in a field, record and file, and define what an exception is.

Answer:

A file is a collection of information. There are different types of files like a text file, dat file, binary file, CSV file etc. All these files stores data in one particular format.

The output produced by a program doesn't save unless it is explicitly saved. We use a file to store data, process data, retrieve data to perform some calculations.

The program reads a file and processes it. The way in which information is read depends on the programming language, type of file as well as functions used to process it.

In C/C++, the file pointer needs to be created to hold the file. There are different modes like read, write, append read/write etc. You can read a file line by line, character by character, block by block.

The loop is created which can read a file character by character and it will terminate when End Of File (EOF) is being reached.

Example:

#include<iostream>

#include <fstream>

using namespace std;

int main() {

char str[256];

char c;

cout << "Enter the name of an existing file: ";

cin.get (str,256); // get the file name. File name is limited to 256 characters

ifstream is(str); // FILE OPEN

while (is.get(c)) // read character by character

cout << c;

is.close(); // FILE CLOSE

}

A file is a collection of records. The record is a collection of fields.

A field is one of the attributes in a record.

Example: student.txt

StudentNo StudentName

1 ABC

2 DEF

student.txt is a file.

Student No and StudentName are fields.

1 ABC

2 DEF

records.

An exception is an abnormal condition which leads to abnormal termination of a program. In FILE context, an exception would happen when you try to read a file which doesn't exist when you try to use a function which doesn't work with the specific type of file etc.