How to read from and write to an Excel file?

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C++

Input and output to Excel file in c + +?
How to get data from Excel files and how to get out of the Excel file.
How is the output file line by line???
Please answer with examples..
I would like in this example, I get the input file, and to give the output file.
I'll file this program, but can not get the input and output.
You, with an input and output, complete my program.
Thanks for the answer you early.

#include <iostream>
#include <fstream>
#include <string>
using namespace std;
#define FILE_IN "exel.xlsx"
#define FILE_OUT "report.xlsx"
int main( ){
    string a;
    ifstream input;
    ofstream output;
    input.open(FILE_IN);
    output.open(FILE_OUT);
    input.close();
    output.close();
    return 0;
    }

string a input.
string a output.