File I/O - File Output Problems (getting 0.00 as output; variables not initialized)

[lajm]

Hello,

I have written a program to input ten floating-point numbers from an input file, read them, and then sum the numbers and calculate the average. The program then outputs the sum and average to an output file. I am having two problems:

1. in Xcode, the program compiles and runs, but the output file contains:
0.00
0.00

2. in Visual C++, the output from "Build Solution" shows warning C4700; that is, that my variables are not initialized (i.e. n1, n2, n3, etc...). When I try to run the program, I get a window with "Debug Error! Run-Time Check Failure #3 - T", and I then have to abort the program.

I have tried initializing the variables in Xcode as:
int n1 = 92.34;
int n2 = 74.523;
etc...
without using any input and the average and sum are computed correctly and written to the output file.

For your reference floatinput.txt looks like this:
10.958
8.4442
63.42
4.99
0.392
46.27
12.123
93.42
1.02
94.265

What could I be doing wrong?

Thanks for your help,

lajm

#include <iostream>
#include <fstream>
// for declaring I/O streams with files
#include <iomanip>
// for using setprecision

using namespace std;

int main()
{
	float n1, n2, n3, n4, n5, n6, n7, n8, n9, n10;
	// declares 10 float variables to store the floating-point values
	float sum = n1 + n2 + n3 + n4 + n5 + n6 + n7 + n8 + n9 + n10;
	float average = sum / 10;
	// declares three float variables and uses the 10 floating-point values in the computation of the sum and average
	// also declares number of floating-point values to be 10

	ifstream dataIn;
	ofstream dataOut;
	// declares two internal file names to associate with an external file name

	dataOut << fixed << showpoint;
	// forces decimal display and shows the decimal even if there are no fractional components

	dataIn.open("floatinput.txt");
	dataOut.open("output.txt");
	// associates internal file names to external file names and opens the files for use

	dataIn >> n1 >> n2 >> n3 >> n4 >> n5 >> n6 >> n7 >> n8 >> n9 >> n10;
	// reads data from external input file
	
	dataOut << setprecision(2);
	// sets precision of average to two numbers after the decimal point
	dataOut << sum << endl;
	dataOut << average << endl;
	// writes the sum and average to the external output file

	dataIn.close();
	dataOut.close();
	// closes input and output stream

        return 0;
}

[integralfx]

float n1, n2, n3, n4, n5, n6, n7, n8, n9, n10;

Not initialised, so will contain garbage values.
Consider using an array or better yet, a vector to store these values.

	float sum = n1 + n2 + n3 + n4 + n5 + n6 + n7 + n8 + n9 + n10;
	float average = sum / 10;

Doing calculations using garbage values will result in a garbage value.

You need to read in the values from your file before you do calculations on them.

[lajm]

Thank you so much! As you suggested, I needed to read in the values before doing calculations on them.