finding sum of integers in a file and out putting it to another file? still wrong output?

Question

i am trying to find sum in a file and output it to another , however when i open the output file the sum is still 0?

include <fstream>
using namespace  std;
void main() {
    ifstream fin("inFile.txt");  // create input stream & connects to file
    ofstream fout("outFile.txt");  // create output stream & connects to file

    int n = 0, sum = 0, num = 0;
    fin >> n;        // read the number of integers from inFile.txt
    for (int i = 0; i < n; i++) {
        fin >> num;
        sum = sum + num;
    }
    fout << "sum is " << sum << endl;
    fin.close();
    fout.close();
}

How does the input file look like? Also are you sure it was opened correctly (you never checked for error states)? — πάντα ῥεῖ, Nov 18 '18 at 19:55
So what is the value of `sum`? You never mentioned what `sum` is -- you only mentioned what your output file contains. — PaulMcKenzie, Nov 18 '18 at 19:56
This Code is Ok, can you show me what does the input file contain, where is it? — Muhammad Magdi, Nov 18 '18 at 20:00
You really should simply figure out where the break down begins. Is it the input file reading of the numbers? Is it the computing of `sum`? Is it the output file itself, something silly like not viewing the correct file or the file could not be created? — PaulMcKenzie, Nov 18 '18 at 20:04
i am confused do i have to add the files to the compiler first or no need? — Sarah_Xx, Nov 18 '18 at 20:14
[Start by adding a #](https://wandbox.org/permlink/wUatE3iWU4UBLpZD) — Aykhan Hagverdili, Nov 18 '18 at 20:35
[void main is undefined](https://stackoverflow.com/a/204483/10147399), fix that too — Aykhan Hagverdili, Nov 18 '18 at 20:37

score 3 · Accepted Answer · answered Nov 18 '18 at 20:47

Not much wrong with the basic structure of the file but it also depends heavily on the input file format. And consider reading input can easily go wrong you should add multiples checks for failure on the input stream.

So either run the program under a debugger or add appropriate print statements.

#include <cstdlib>
#include <fstream>

int main() {
    std::ifstream fin("inFile.txt");  // create input stream & connects to file
    if (!fin) return EXIT_FAILURE;
    std::ofstream fout("outFile.txt");  // create output stream & connects to file
    if (!fout) return EXIT_FAILURE;

    int n = 0, sum = 0, num = 0;
    fin >> n;        // read the number of integers from inFile.txt
    if (!fin) return EXIT_FAILURE;
    for (int i = 0; i < n; i++) {
        if (!fin >> num) return EXIT_FAILURE;
        sum = sum + num;
    }
    fout << "sum is " << sum << std::endl;
    return EXIT_SUCCESS;
}

And of course there's a missing check just before `return EXIT_SUCCESS` if final write to `fout` succeeded. — Bo R, Nov 19 '18 at 11:40

finding sum of integers in a file and out putting it to another file? still wrong output?

1 Answers1