Chapter 6, Problem 1P

Write a program that will search a file of numbers of type int and write the largest and the smallest numbers to the screen. The file contains nothing but numbers of type int separated by blanks or line breaks. If this is being done as a dass assignment, obtain the file name from your instructor.

Program Plan Intro

Largest and Smallest numbers

Program Plan:

• Include the required headers.
• Define “main()” method.
  • Declare the required “int” and “char” variables.
  • Prompt the user for input file.
  • Read the required input file.
  • Create the object for “ifstream”.
  • Open the required file.
  • Check the file can be opened or not using “if” condition.
  • If the file includes any error, print file “cannot be opened”.
  • Initialize the input and check for largest and smallest numbers present in the file.
  • Print the output using “cout”
  • Return the required variable.
• Close the “main()” method.

Program Description Answer

The below C++ program describes about the displaying of largest and smallest values among the numbers present in a given file.

Explanation of Solution

Program:

//Include the needed headers

#include <iostream>

#include <fstream>

#include <cstdlib>

#include <climits>

using namespace std;

//main() Method

int main()

{

//Declaration of int variable sum

int sum = 0;

//Declaration of char variable file_name

char file_name [31];

//Declaration of input and index

int input, i = 0;

//Declaration of largest

int largest = -INT_MAX;

//Declaration of smallest

int smallest = INT_MAX;

//prompt the user for input file name

cout << "Enter a file name."

<< " This Program limits file names to"

<< endl

<< " a maximum of 30 characters. " << endl;

//read the input file name

cin >> file_name;

//creating object for ifstream

ifstream infile;

//a handle for opening the input file

infile.open(file_name);

//check the condition

if(!infile)

{

//display the error

cout << "Cannot open file " << file_name

<< " Aborting program " << endl;

//stop and exit

exit (1);

}

//initialize the input

infile >> input;

//start the loop

while(infile)

{

//check the condition

if(input > largest)

//get the largest value

largest = input;

//check the file

if(input < smallest)

//get the smallest value

smallest = input;

cout << input << " " << endl;

infile >> input;

}

//display the output

cout << "smallest in file = " << smallest

<< " largest in file = " << largest << endl;

getchar();

getchar();

//return the required value

return 0;

}

Sample Output

Output: