C++ Program to Read a CSV File and Calculate the Total

CSV files are everywhere. This program reads a small sales file, skips the header, ignores bad lines and shows the total and the average.

Program

#include <fstream>
#include <iomanip>
#include <iostream>
#include <sstream>
#include <string>
#include <vector>

struct Sale {
    std::string item;
    int quantity;
    double price;
    double amount() const { return quantity * price; }
};

std::vector<std::string> split(const std::string& line, char sep) {
    std::vector<std::string> parts;
    std::istringstream in(line);
    std::string part;
    while (std::getline(in, part, sep)) parts.push_back(part);
    return parts;
}

int main() {
    std::ofstream("sales.csv") << "item,quantity,price\nPen,10,5.50\nBook,2,250\nBag,1,899.99\nBroken line\nNotebook,abc,40\n";

    std::ifstream in("sales.csv");
    std::string line;
    std::getline(in, line);                             // skip the header

    std::vector<Sale> sales;
    while (std::getline(in, line)) {
        auto p = split(line, ',');
        if (p.size() != 3) {
            std::cout << "Skipped (wrong columns): " << line << '\n';
            continue;
        }
        try {
            sales.push_back({p[0], std::stoi(p[1]), std::stod(p[2])});
        } catch (const std::exception&) {
            std::cout << "Skipped (bad number): " << line << '\n';
        }
    }

    double total = 0;
    std::cout << std::fixed << std::setprecision(2);
    for (const auto& s : sales) {
        std::cout << std::left << std::setw(10) << s.item << std::right << std::setw(8) << s.amount() << '\n';
        total += s.amount();
    }
    std::cout << "Total: " << total << '\n';
    std::cout << "Average per row: " << total / sales.size() << '\n';
}

Notes

• std::getline(in, part, ',') splits a text by a character.
• std::stoi and std::stod throw an exception for a bad number, so we catch it and skip the line.
• If a value can contain a comma inside quotes, use a CSV library.

Related: C++ File Handling and C++ Exceptions.

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