Question

C++ programa use include<iostream> and #include<fstream> grades.txt is Heights.txt

Write a C++ program to perform the following steps 1. Open a file called Heights.txt. The file consists of Grades.txt positive and negative values. A portion of the file is shown her → 11.5 -9.9 3.11 2. If the open operation fails, display an error 8.50 77.8 5.71 message and terminate the program. 3. Once the file is successfully opened, read the contents and write the positive values to a new file called Positive.txt. 4. If the output file cannot be opened, display an error message and terminate the program. 5. Properly terminate the file handles.

Answer 1

Completed the program to read data from grades.txt file and store only positive number in positive.txt file.

Below is the implementation and output attatched.

(To run this program create grades.txt file and positive.txt file int the same directory where you place this program file)

#include <iostream>
#include <fstream>
using namespace std;
int main()
{
    ifstream grades;
    ofstream output;
    //Opening grades.txt and positive.txt files
    output.open("positive.txt");
    grades.open("grades.txt");
    //if gradex.txt file fail to open
    if (grades.fail())
    {
        cout << "Input file Couldn't open !" << '\n';
        return 0;
    }
    //if positive.txt file fail to open
    if (output.fail())
    {
        cout << "Output file Couldn't open !" << '\n';
        return 0;
    }
    string line;
    while (!grades.eof())
    {
        //getting each line from grades.txt
        getline(grades, line);
        //calculating and storing result in ans string if the number present in grades.txt is positive
        string ans = "", sudo = "";
        for (int i = 0; i < line.length(); i++)
        {
            //when we encounter ' ' in a line means a number is stored in variable sudo, after space (' ') another number starts
            if (line[i] == ' ')
            {
                float num = std::stof(sudo); //stof function is used to convert string to float type.
                if (num > -1)
                {
                    ans += sudo + ' '; //append particular number to ans variable if num is positive
                }
                sudo = "";
            }
            sudo += line[i];
        }
        //for the last number in a line
        float num = std::stof(sudo);
        if (num > -1)
        {
            ans += sudo + ' ';
        }
        sudo = "";
        //Storing result of each line from input file(grades.txt) in output file(positive.txt).
        if (ans != "")
        {
            output << ans << '\n';
        }
    }

    //Treminating the file handles
    output.close();
    grades.close();
}

Output :

Grades.txt

grades.txt 11.5 -9.9 3.11 8.50 77.8 5.71 -1

positive.txt

positive.txt þ.1.5 3.11 8.50 77.8 5.71