take values from a text file and store them in a variable and use for later calculation

[singhal2]

I have a text file in the form
5502 5202.3
1523 2536.1
1254 1256.2
17846 8956.2 and so on
left one is time and right one is pressure, I need to show the time value as it is but i need to use the pressure value to calculate air speed.
I don't know how to use the strings to pick up the list properly. I did the calculation formula for the air speed but i can't pick the pressure value up from the text file.
here's what i did:

#include <iostream>
#include <fstream>
#include <string>
using namespace std;

int main()

{

	int number_of_lines = 0;
	int time;
	double Pt;
	double ao = 0;
	double P0 = 1013.25;
	double Cas;
	double A;
	double B;
	double C;
	double D;
	int n=0;
	float X = 2 / 7;

	string line;
	ifstream myfile("code.txt");
	while (getline(myfile, line))
	{
		++number_of_lines;
	}
	
	/* I NEED HELP IN THIS PART TO TAKE THE PRESSURE VALUE FOR CALCULATION LATER, LIKE A LOOP AND IN THE RESULT I NEED TO DISPLAY TIME VALUE WITH CALCULATED AIR SPEED VALUE IN THE SAME FORMAT. */

	ifstream file("code.txt");
	string s;
	while (n < number_of_lines && file >> time >> s >> Pt )
	{
		n++;
		cout << time<<endl;
		

	}


	A = Pt / P0;
	B = A + 1;
	C = pow ( B , X);
	D = 5 * (C - 1);
	Cas = ao * (sqrt(D));
	cout << Cas;


	return 0;
	system("pause");
}

[Scott7975]

Im new but I believe you declared and opened the file wrong. So I don't think it is reading your file at all. Also make sure the file is in the same place as your project.

Your declare should be: ifstream myfile;

To open the file: myfile.open("code.txt");


Try that and see if it works. Im in my first semester so I might be wrong, but Im pretty sure.

[singhal2]

umm, thanks for the reply. but the command you said isn't working . I am getting errors. My program is working fine , i am getting output as
5502
5202.3
1523
2536.1
1254
1256.2
...

but i want one value at a time.

[vin]

The code you listed doesn't produce that output.

If you group your values in the text file into threes every second one is put into s and every third one is put into Pt and neither of those is printed to console.

Also Cas should always print 0 to console since ao is always 0.

Put your airspeed calculation inside the while loop.