input integer from text file and output text file

shmilon (6)
I want to input my integer data from a text file and then my program will run and the final result of this program will generate an output.txt file.

You can run this program first time manually. This is a simple sorting problem.

My program is working well if i input manually but now just want to input from a text file. If anyone can, please help me.


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#include <iostream>
#include <array>
#include <vector>
#include <utility>

int main()
{
    std::vector< std::array<int,2> > v;
    std::size_t n;
    if (std::cin >> n && n > 0)
    {
        std::array<int,2> row;
        while (n-- && std::cin >> row[0] && std::cin >> row[1])
            v.emplace_back(row);

        // bubblesort the content
        std::size_t len = v.size();
        while (len-- > 0)
        {
            bool swapped = false;
            for (std::size_t i=0; i<len; ++i)
            {
                // std::array support multi-cell comparison.
                if (v[i] < v[i+1])
                {
                    // use library swap to swap entire row.
                    std::swap(v[i], v[i+1]);
                    swapped = true;
                }
            }

            // early exit if no swaps happened on the last pass
            if (!swapped)
                break;
        }

        // report final output.
        for (auto const& row : v)
            std::cout << row[0] << ' ' << row[1] << '\n';
    }
}


This is my sample input. Here 8 is the array size. And below 8 pair is the numbers of 2d array.

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8
41 11
34 4
69 4
78 6
62 8
5 5
81 3
5 10


And this is my sample output

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8
 
81 3
78 6
69 4
62 8
41 11
34 4
5 10
5 5
jonnin (11437)
look at an example using <fstream>
or, the 10 cent version:

ifstream file("path\\filename.txt");
while (file >> number)
matrix[index++] = number; // One dimensional array example.
seeplus (6592)
Consider:

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#include <iostream>
#include <array>
#include <vector>
#include <utility>
#include <fstream>

int main() {

	std::ifstream ifs("input.txt");
	std::ofstream ofs("output.txt");

	if (!ifs || !ofs)
		return (std::cout << "Cannot open files\n"), 1;

	std::size_t n {};

	if (ifs >> n && n > 0) {
		std::vector< std::array<int, 2> > v(n);

		while (n-- && ifs >> v[n][0] && ifs >> v[n][1]);

		// bubblesort the content
		auto len {v.size()};

		while (len-- > 0) {
			bool swapped {};

			for (std::size_t i = 0; i < len; ++i)
				// std::array support multi-cell comparison.
				if (v[i] < v[i + 1]) {
					// use library swap to swap entire row.
					std::swap(v[i], v[i + 1]);
					swapped = true;
				}

			// early exit if no swaps happened on the last pass
			if (!swapped)
				break;
		}

		// report final output.
		for (auto const& row : v)
			ofs << row[0] << ' ' << row[1] << '\n';
	}
}

shmilon (6)
here show error on my ide. please see

http://prntscr.com/z0frkv

I use codeblocks
Last edited on
dutch (2548)
There's no way this guy wrote the original program.
shmilon (6)
but my ide is can not run this program
jonnin (11437)
find the flags to use a newer language version or get a new IDE. 2011 was 10 years ago -- not supporting this is no longer optional or acceptable.
shmilon (6)
here is the details of my ide http://prntscr.com/z0kvn5 also check this http://prntscr.com/z0kzan
shmilon (6)
please can you sort my input.txt file and send it a text file to me?
https://drive.google.com/file/d/1JbOybnS3e4Rd82mY2DA2mLy8VYsyKUvk/view?usp=sharing
shmilon (6)
Thank you code is perfectly running. I solved my ide problem
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