Function/Array problems

[Trev17]

Hello, I am trying to write a program that reads in a file, and uses a 2d array to store the highest and lowest temp from each month. It also outputs the average high and the average low. The file that i am reading in is called homework2.txt and looks like this:
-4 25
6 33
21 50
33 67
50 72
65 80
72 95
65 101
58 82
35 62
34 59
-6 31
the first column being the lows and the second being the highs.

I also need 4 functions: getData(reads in the file and assigns to 2d array), averageHigh(sel f explanatory), averageLow(self explanatory), indexHighTemp(h ighest temp), and indexLowTemp(lo west temp).

I wrote a lot of the program already minus the indexHighTemp and indexLowTemp because i can't seem to figure out where to even start to find them.

Some problems i am having is that the answers for my averageHigh and averageLow are both 0. I dont know if its because i assigned the file to the 2d array wrong or if i just did the two functions wrong.

#include "stdafx.h"
#include <iostream>
#include <fstream>

using namespace std;

//function prototypes
void getData();
double averageHigh();
double averageLow();
int indexHighTemp();
int indexLowTemp();

//declared arrays in file
int temps[12][2];

//main part of program
int _tmain(int argc, _TCHAR* argv[])
{
	//declared variables
	int a;
	int b;
	int c;
	int d;
	int e;
	
	cout << "Press 1 to read the temp. file or 2 to exit" << endl;
	cin >> a;
	
	//exit if statement
	if (a != 1)
		return 0;

	//calling the function
	getData();

	cout << "Press 1 if you want to find the average high temp" << endl;
	cin >> b;

	if (b != 1)
		return 0;

	cout << "The average high is: "<< averageHigh() << endl;

	cout << "Press 1 if you want to find the average low temp" << endl;
	cin >> c;

	if (c != 1)
		return 0;

	cout << "The average low is: " << averageLow() << endl;

	cout << "Press 1 if you want to find the highest temp" << endl;
	cin >> d;

	if (d != 1)
		return 0;

	//cout << "The Hottest temperature was: " << indexHighTemp() << endl;

	cout << "Press 1 if you want to find the lowest temp" << endl;
	cin >> e;

	if (e != 1)
		return 0;

	//cout << "The Coldest temperature was: " << indexLowTemp() << endl;

system("pause");
return 0;
}

//getData function
void getData()
{
	//declared file stream variable
	ifstream File;
	
	//opens file
	File.open("homework2.txt");

	if (!File)
	{
		cout << "Error cannot open file!" << endl;
	}

		//array initialization
		for (int row = 0; row < 12; row++)
			for (int col = 0; col < 2; col++)
				temps[row][col] = 0;

}

//average high function
double averageHigh()
{
	double avgHigh;

	//calculates the average high(the highs are the 2nd column)
	avgHigh = (temps[1][2]+ temps[2][2]+temps[3][2]+temps[4][2]+temps[5][2]+temps[6][2]+temps[7][2]
	          +temps[8][2]+temps[9][2]+temps[10][2]+temps[11][2]+temps[12][2])/12;

	//return the average high
	return avgHigh;
}

//average low function
double averageLow()
{	
	double avgLow;

	//calculates the average low(the lows are the 1st column)
	avgLow = (temps[1][1]+ temps[2][1]+temps[3][1]+temps[4][1]+temps[5][1]+temps[6][1]+temps[7][1]
	          +temps[8][1]+temps[9][1]+temps[10][1]+temps[11][1]+temps[12][1])/12;

	//returns the average low
	return avgLow;
}

//highest temp function
//int indexHighTemp()
//{
	//int Hottest;
	
	//calculates the hottest temperature
	//Hottest =

	//return Hottest;

//}

//lowest temp function
//int indexLowTemp()
//{
	//int Coldest;

	//calculates the coldest temperature
	//Coldest = 

	//return Coldest;
//}

any help is greatly appreciated. Thank you.

[sicarie]

Trev17-

I see a few problems with this - your if (input != 1) statements aren't put in a manner that you will be able to do anything except for the first. If the first fails, 0 is returned, which means the program terminates normally. I think you want more of a menu to call your functions, have you considered a while loop to read in a line, and a switch statement to call the proper function?

Have you printed out the values in the function, to make sure there is data there?

[Trev17]

Have you printed out the values in the function, to make sure there is data there?

I have both functions (averageHigh, averageLow) being called in the program and the output for both is 0. If thats what you meant?

for the if (!File) how would you put that in so that it does something?

[sicarie]

I have both functions (averageHigh, averageLow) being called in the program and the output for both is 0. If thats what you meant?

for the if (!File) how would you put that in so that it does something?

Ok, after looking at it a bit more, I'm pretty sure you have no data in your arrays. (I was talking about printin out the full arrays - a 'cout << temp[i][j]' type of action), but take a look at the for loop you have where you assign temperatures to the array.

You open the file, make sure it's open, but then look at what you declare in the comment as "array initialization" . You set everything to 0. Your functions are probably working right, because there's no info in them.

You have File declared, you just need to read the elements in from file into the proper place. I'll give you a hint, you'll need to wrap the for loops in a while loop, and after that, instead fo assigning a place in the array 0, you need to assign it the next value from the file.

Does that help?

[Trev17]

You have File declared, you just need to read the elements in from file into the proper place. I'll give you a hint, you'll need to wrap the for loops in a while loop, and after that, instead fo assigning a place in the array 0, you need to assign it the next value from the file.

Does that help?

I changed it to this but now it sort of freezes after it calls the getData function.

while (File)
{
for (int row = 0; row < 12; row++)
for (int col = 0; col < 2; col++)
temps[row][col]++;
}
I think this is what you meant but not sure.

[sicarie]

I changed it to this but now it sort of freezes after it calls the getData function.

while (File)
{
for (int row = 0; row < 12; row++)
for (int col = 0; col < 2; col++)
temps[row][col]++;
}
I think this is what you meant but not sure.

Ok, so you want to pull temperatures from File, correct? So I would change the condition in your while to be (File != 'EOF') - the EOF character stands for 'End of File' and will let the while loop know that is has reached the end. Right now it's freezing because the file exists, so it's open, so it always returns true (there is no condition in which File will return false, unless you delete/move it yourself, which isn't what you want).

Second, code tags ( [ code] and [ /code] without the spaces inside) help a great deal with readability and spacing.

Third, you have

temps[row][col]++;

What do you want this to do? The ++ postincrement operator is working on the values of each, but you're not saving those values, and that's not what you really want to do anyway. Right here is where you want to read in a value from File.

Check out this tutorial from cplusplus.com, it will help with File IO.

[ilikepython]

For the high, low functions: just assign a variable to one of the temps and check to see if any of the other temps are larger (or smaller) than it. Like this:

variable = first temp
if variable < second temp
    variable = second temp
if variable < third temp
    variable = third temp
and so on and so on