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how to save output in a text file

khaled124 (16)
Could someone tell me how to get the output of this program into a text file ?

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#include <iostream>
#include <math.h>

using std::cout;
using std::cin;
using std::endl;

int main(void)
{
	double x3, x2, x1, f;
	double a, b, p;
	double fa, fb, fp;
	double tol;
	int n, i;
	char indicator = 'n';
	int retry;

selection:

	cout << endl
		<< " Enter the value of x^3 coeff :";
	cin >> x3;

	cout << endl
		<< " Enter the value of the X^2 coeff :";
	cin >> x2;

	cout << endl
		<< " Enter the value of x coeff :";
	cin >> x1;

	cout << endl
		<< " Enter the value of free coeff :";
	cin >> f;

	cout << endl
		<< " Insert the number of iterations :";
	cin >> n;

	cout << endl
		<< " Enter the wanted tolerance :";
	cin >> tol;
    
	cout << endl
		<< " Enter the value of a :";
	cin >> a;

	cout << endl
		<< " Enter the value of b :";
	cin >> b;

	p = (a+b)/2;

	fa = x3 * pow(a,3) + x2 * pow(a,2) + x1 * a + f;
	fb = x3 * pow(b,3) + x2 * pow(b,2) + x1 * b + f;
	fp = x3 * pow(p,3) + x2 * pow(p,2) + x1 * p + f;
	
	

	for (i = 1; i < n && tol < abs(fp) && a < b; i++)
	{

		p = (a+b)/2;
	fa = x3 * pow(a,3) + x2 * pow(a,2) + x1 * a + f;
	fb = x3 * pow(b,3) + x2 * pow(b,2) + x1 * b + f;
	fp = x3 * pow(p,3) + x2 * pow(p,2) + x1 * p + f;
	
		cout << endl
		<< "Iteration number " << i;
	cout <<endl
		<< "~~~~~~~~~~~~~~~~~~~";
	cout <<endl
		<< "a = " <<a;
	cout <<endl
		<< "b = " <<b;
	cout <<endl
		<< "p = " <<p;
	cout <<endl
		<< "                 ";
	cout <<endl
		<< "f(a) = " <<fa;
	cout <<endl
		<< "f(b) = " <<fb;
	cout <<endl
		<< "f(p) = " <<fp;
	cout <<endl
		<< "                 ";
	cout << endl
		<< "Solution = " <<p;
	
	cout << endl 
		<<"______________________";

	if ((fa < 0) && (fp < 0) || ((fa > 0) && (fp > 0 )))
		a = p, b = b;
	else
		a = a, b = p;

	
	
	}
		
	cout<<endl
		<<"Select the number of the desired option.\n";
    cout<<"1. Try another problem\n";
    cout<<"2. Exit the program\n";
    cout<<">>. ";
    cin>>retry;

    switch (retry) {
    case 1:
    goto selection;

    case 2:
    goto exit;
	
	}
	exit:
return 0;
}
khaled124 (16)
Please i want a solution for this case, and i will learn iostream issue latter
thanks in advance.
hanst99 (2869)
You create a new output filestream (ofstream) like this:
 
 
ofstream ofs("The_name_of_the_file_you_want_as_output");


Then you can use ofs just like you would cout. At the end of the program, you call ofs.close() and you're done.
hanst99 (2869)
Oh and you have to include fstream.

Btw: instead of including math.h, include cmath. Technically they're the same thing, but the .h files are just for compatibility with older C++ programs, the extensionless headers are now standard.
Last edited on
Albatross (4553)
Hello!

Just a few things to note, khaled124. We don't provide complete solutions for ANY problem. It's kind-of an unwritten rule around here. :)

Second, we actually have a tutorial on file I/O on this site! It's kinda buried, but it's here: http://cplusplus.com/doc/tutorial/files/

Third, I wish you the best of luck!

-Albatross
khaled124 (16)
Thanks for reply hanst99.

Albatross I understand your opinion, but I was hopless to find the solution of this problem

Any way thank you all
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