Here's an answer with less complex while loop and no use of stringstreams.

I've found std::stoi/std::stof faster than >> operator to convert strings to numbers. Also, we have a clear indication of failure in the form of exceptions.

If you only need the sum, don't store all numbers. If the file is big, it's just memory waste.

#include<cmath>
#include<assert.h>

Unused headers.

• https://github.com/include-what-you-use/include-what-you-use

#include <fstream>
#include <iostream>
#include <string>

int main() {
    int sum = 0;
    std::ifstream file_s("file1.txt");
    if (file_s.bad()) {
      return -1;
    }

    std::string word;
    while (std::getline(file_s, word, ' ')) {
        int number = 0;
        try {
           number = std::stoi(word);
        }
        catch(const std::invalid_argument& ex) {
            std::cout << ex.what() << ":" << word << std::endl;
        }
        sum += number;
    }

    std::cout << sum << std::endl;
    return 0;
}

Here's an answer with less complex while loop and no use of stringstreams.

I've found std::stoi/std::stof faster than >> operator to convert strings to numbers. Also, we have a clear indication of failure in the form of exceptions.

If you only need the sum, don't store all numbers. If the file is big, it's just memory waste.

#include<cmath>
#include<assert.h>

Unused headers.

• https://github.com/include-what-you-use/include-what-you-use

#include <fstream>
#include <iostream>
#include <string>

int main() {
    int sum = 0;
    std::ifstream file_s("file1.txt");
    if (file_s.bad()) {
      return -1;
    }

    std::string word;
    while (std::getline(file_s, word, ' ')) {
        try {
           sum += std::stoi(word);
        }
        catch(const std::invalid_argument& ex) {
            std::cout << ex.what() << ":" << word << std::endl;
        }
    }

    std::cout << sum << std::endl;
    return 0;
}

Here's an answer with less complex while loop and no use of stringstreams.

I've found std::stoi/std::stof faster than >> operator to convert strings to numbers. Also, we have a clear indication of failure in the form of exceptions.

If you only need the sum, don't store all numbers. If the file is big, it's just memory waste.

#include<cmath>
#include<assert.h>

Unused headers.

• https://github.com/include-what-you-use/include-what-you-use

#include <fstream>
#include <iostream>
#include <string>

int main() {
    int sum = 0;
    std::ifstream file_s("file1.txt");
    std::string word;
    while (std::getline(file_s, word, ' ')) {
        int number = 0;
        try {
           number = std::stoi(word);
        }
        catch(const std::invalid_argument& ex) {
            std::cout << ex.what() << ":" << word << std::endl;
        }
        sum += number;
    }
    std::cout << sum << std::endl;
}

Here's an answer with less complex while loop and no use of stringstreams.

I've found std::stoi/std::stof faster than >> operator to convert strings to numbers. Also, we have a clear indication of failure in the form of exceptions.

If you only need the sum, don't store all numbers. If the file is big, it's just memory waste.

#include<cmath>
#include<assert.h>

Unused headers.

• https://github.com/include-what-you-use/include-what-you-use

#include <fstream>
#include <iostream>
#include <string>

int main() {
    int sum = 0;
    std::ifstream file_s("file1.txt");
    if (file_s.bad()) {
      return -1;
    }

    std::string word;
    while (std::getline(file_s, word, ' ')) {
        int number = 0;
        try {
           number = std::stoi(word);
        }
        catch(const std::invalid_argument& ex) {
            std::cout << ex.what() << ":" << word << std::endl;
        }
        sum += number;
    } 

    std::cout << sum << std::endl;
    return 0;
}