Answer :
Answer:
/*C++ program that prompts user to enter the name of input file(input.txt in this example) and print the sum of the values in the file to console. If file dosnot exist, then close the program */
//header files
#include <fstream>
#include<string>
#include <iostream>
#include <cstdlib> //needed for exit function
using namespace std;
//function prototype
int fileSum(string filename);
int main()
{
string filename;
cout << "Enter the name of the input file: ";
cin >> filename;
cout << "Sum: " << fileSum(filename) << endl;
system("pause");
return 0;
}
/*The function fileSum that takes the string filename and
count the sum of the values and returns the sum of the values*/
int fileSum(string filename)
{
//Create a ifstream object
ifstream fin;
//Open a file
fin.open(filename);
//Initialize sum to zero
int sum=0;
//Check if file exist
if(!fin)
{
cout<<"File does not exist ."<<endl;
system("pause");
exit(1);
}
else
{
int value;
//read file until end of file exist
while(fin>>value)
{
sum+=value;
}
}
return sum;
}//end of the fileSum
Explanation:
This is a C++ program that prompts user to enter the name of input file(input.txt in this example) and print the sum of the values in the file to console. If file dosnot exist, then close the program.
Check attachment for sample output screenshot.
Following are the program to the given question:
Program Explanation:
- Header file.
- Defining a method "fileSum" that takes string variable in the parameter and calculates the sum of the file value.
- Outside the method the main method is defined that input file and check if exist and call the above method.
Program:
#include <fstream>//header file
#include <iostream>
#include <cstdlib> //needed for exit function
using namespace std;
int fileSum(string filename)//defining a method fileSum that takes string variable inside the parameter
{
ifstream in(filename.c_str());//calling ifstream that inputs file
if(in.bad() || !in.is_open())//defining if block that check file is open or bad
{
cout<<"Error: File \""<<filename<<"\" not found.";// print message that says file not found
exit(1);//calling exit method
}
int t = 0,n;//defining integer variable
while(in>>n)//defining loop that adds file value
t+=n;//adding value in t variable
in.close(); //close the file
return t;
}
int main()//defining main method
{
string filename;//defining string variable
cout << "Enter the name of the input file: ";//print message
cin >> filename;//input file name
cout << "Sum: " << fileSum(filename);//print value
return 0;
}
Output:
please find the attached file.
Learn more:
brainly.com/question/12908540
