How to read and write to file Input/Output in C++?

Question

This is my data in txt file:

aziz ahmad,50,1.82
syazana rosli,55,1.3 
darwina daud,60,1.5
faiz aiman, 65,1. 6
zara zainuddin,58,1.4
muhammad muiz,52,1.9
nabila saari, 47,1.4

This is what i'm working on:

#include <iostream>
#include <fstream>
#include <iomanip>
using namespace std;

struct Student
{
    string name;
    double weight;
    double height;
};

int main()
{
    Student studList[7];
    double BMI, average=0.0, totalBMI = 0.0;
    string category;

    ifstream in("studentData.txt");
    ofstream out("bmiReport.txt");

    for(int i=0; i<7; i++)
    {
        getline(in, studList[i].name, ',');
        in>>studList[i].weight>>studList[i].height;
    }

    for(int j=0; j<7; j++)
    {
        BMI= studList[j].weight / (studList[j].height*studList[j].height);
    
        if(BMI>=0.0 && BMI<=18.5)
            category="Underweight";
        else if(BMI>18.5 && BMI<=23.0)
            category="Normal";
        else if(BMI>23.0 && BMI<=25.0)
            category="Overweight- At Risk";
        else if(BMI>25.0 && BMI<=30.0)
            category="Overweight- Moderately Obese";
        else if(BMI>30.0)
            category="Overweight- Severely Obese";
        
        totalBMI += BMI;
    
        out<<"\t\tThe BMI Report"<<endl;
        out<<"Name\tWeight(kg)\tHeight(meters)\tBMI\tCategories"<<endl;
        out<<setprecision(2)<<fixed;
        out<<studList[j].name<<"\t"<<studList[j].weight<<"\t"<<studList[j].height<<"\t"<<BMI<<"\t"<<category<<"\t"<<endl;
}

    average = totalBMI/7;
    out<<"The average BMI: "<<average;

    in.close();
    out.close();
}

This is the ouput i got:

The BMI Report
Name    Weight(kg)  Height(meters)  BMI Categories
    0.00    0.00    inf Overweight- Severely Obese  
        The BMI Report
Name    Weight(kg)  Height(meters)  BMI Categories
    0.00    0.00    inf Overweight- Severely Obese  
        The BMI Report
Name    Weight(kg)  Height(meters)  BMI Categories
    0.00    0.00    inf Overweight- Severely Obese  
        The BMI Report
Name    Weight(kg)  Height(meters)  BMI Categories
    0.00    0.00    inf Overweight- Severely Obese  
        The BMI Report
Name    Weight(kg)  Height(meters)  BMI Categories
    0.00    0.00    inf Overweight- Severely Obese  
        The BMI Report
Name    Weight(kg)  Height(meters)  BMI Categories
    0.00    0.00    inf Overweight- Severely Obese  
        The BMI Report
Name    Weight(kg)  Height(meters)  BMI Categories
    0.00    0.00    inf Overweight- Severely Obese  
The average BMI: inf

As you can see i need to read the data from the file in order to complete the calculation. This output becomes blank as I have included above. Could you please explain on how i can make the coding read the data? Sorry i am beginner in coding. Thank you in advance for helping me.

You used `getline`, delimited by `','`, to separate your `name` from the remainder of the line. So.. what do you think takes care of that between the `weight` and `height` values ? It seems your *real* question is [How can I read and parse a CSV with C++](https://stackoverflow.com/questions/1120140/how-can-i-read-and-parse-csv-files-in-c) — WhozCraig, Jul 31 '22 at 17:59

john · Answer 1 · 2022-07-31T18:08:29.433

Maybe this

for(int i=0; i<7; i++)
{
    string temp;
    getline(in, studList[i].name, ',');
    getline(in, temp, ',');
    studList[i].weight = stod(temp);
    getline(in, temp, '\n');
    studList[i].height = stod(temp);
}

Your problem is the commas, so use getline to fix that (you already did it for the name). Then you have a different problem getline only reads strings, so read into a temporary string and use stod to convert the string to the number you want.

How to read and write to file Input/Output in C++?

1 Answers1