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Reading temperatures from file (Solved)

Mar 21, 2012 at 4:48am
R N (15)
Hi guys. I am making a program that reads in data from a file that contains temperatures for City 1 and City 2. I need to use a prototype function to calculate the average, highest, and lowest temperatures for both cities. Here is the file I need to read from. (temperature1.txt)
------------------------------
City 1
-20
City 2
-20
City 1
100
City 2
100
City 1
50
City 2
50
--------------------------------

Here is how the output is supposed to look. 
Enter the input filename: temperature1.txt
**************************************************
City 1:
3 temperature1 are recorded.
The average temperature is 43.33
The highest temperature is 100.00
The lowest temperature is -20.00

City 2:
3 temperature1 are recorded.
The average temperature is 43.33
The highest temperature is 100.00
The lowest temperature is -20.00

Do you want to process another file?(y/n)


Here is my code. 

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#include <iostream>
#include <fstream>
#include <string>
#include <iomanip>
using namespace std;
void process(ifstream & ifile); // Prototype
int main()
{
    string fname;
    ifstream ifile;
    char again;
    do
    {
        cout << "Enter the input filename: ";
        getline(cin, fname);
        ifile.open(fname.data());
        if (ifile)
        {
           cout << "**************************************************\n";
           process(ifile);
        }
        else
            cout << "Error opening " << fname << endl;
        ifile.close();
        ifile.clear();
        cout << "\nDo you want to process another file?(y/n) ";
        cin >> again;
        cin.ignore(80,'\n');
    } while (again == 'y' || again == 'Y');
    return 0;
}
void process(ifstream & ifile)
{
    string city;    // for reading in the city name
    int count1 = 0, // counts the number of temperature recorded for City 1.
        count2 = 0; // counts the number of temperature recorded for City 2/  
    float temp1,    // for reading in the temperature of City 1.
       highest1,    // for storing the highest temperature of City 1.
       lowest1,     // for storing the lowest temperature of City 1.
       sum1 = 0,    // for keeping the running total of the temperatures of City 1
       average1,    // for storing the average temperature of City 1.
       // Below variables are for City 2
       temp2,      
       highest2,
       lowest2,
       sum2 = 0,
       average2;

//    Pseudocode    
      getline(cin, city); 
      while (ifile >> temp1 || ifile >> temp2)
      {
            if (city == "City 1")
            {
                cin >> temp1; 
                if (temp1 > highest1) highest1 = temp1;
                if (temp1 < lowest1) lowest1 = temp1;
                sum1 += temp1; 
                count1++;
            }
            else if (city == "City 2")
            {
                cin >> temp2; 
                if (temp2 > highest2) highest2 = temp2;
                if (temp2 < lowest2) lowest2 = temp2;
                sum2 += temp2; 
                count2++; 
            }
      getline(cin, city); 
      }
      average1 = sum1 / count1; 
      average2 = sum2 / count2; 
      
      cout << "City 1:" << endl; 
   //   cout << count1 << " " << fname << " are recorded." << endl; 
      cout << "The average temperature is " << average1 << endl; 
      cout << "The highest temperature is " << highest1 << endl; 
      cout << "The lowest temperature is " << lowest1 << endl; 
      
      cout << "City 2:" << endl; 
    //  cout << count2 << " " << fname << " are recorded." << endl; 
      cout << "The average temperature is " << average2 << endl; 
      cout << "The highest temperature is " << highest2 << endl;
      cout << "The lowest temperature is " << lowest2 << endl; 
      
}
Edit & run on cpp.sh


When I run the program, it compiles but the output does not appear.
Also I can't get the name of the file to show up (code that is commented out) in the output since it is out of scope. How would I fix these issues?
Last edited on Mar 21, 2012 at 11:18pm
Mar 21, 2012 at 6:41am
Azagaros (410)
A loop for reading a file generally looks like, this is based on some of your variables and not..
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int inTemp;
string city;

while(!infile.eof())  // test against the end of file
{
        getline(infile, city);  // read the first line.
        infile >> inTemp;     // read the temp.

        // now we process what we read in.
        if(city == "City 1")
        {
               //.....
        }
        else if(city == "City 2")
        {
             //.....
        }
}  // end of file loop


I hope that points you in a direction.
Mar 21, 2012 at 9:11pm
R N (15)
Hold on I am going to post new code soon.
Last edited on Mar 21, 2012 at 9:16pm
Mar 21, 2012 at 9:38pm
R N (15)
Here is my code. It almost works the way I want it to. 
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#include <iostream>
#include <fstream>
#include <string>
#include <iomanip>
using namespace std;
void process(ifstream & ifile); // Prototype
int main()
{
    string fname;
    ifstream ifile;
    char again;
    do
    {
        cout << "Enter the input filename: ";
        getline(cin, fname);
        ifile.open(fname.data());
        if (ifile)
        {
           cout << "**************************************************\n";
           process(ifile);
        }
        else
            cout << "Error opening " << fname << endl;
        ifile.close();
        ifile.clear();
        cout << "\nDo you want to process another file?(y/n) ";
        cin >> again;
        cin.ignore(80,'\n');
    } while (again == 'y' || again == 'Y');
    return 0;
}
void process(ifstream & ifile)
{
    string city;    // for reading in the city name
    int count1 = 0, // counts the number of temperature recorded for City 1.
        count2 = 0,
        intemp;  
        // counts the number of temperature recorded for City 2/  
    float temp1,    // for reading in the temperature of City 1.
       highest1,    // for storing the highest temperature of City 1.
       lowest1,     // for storing the lowest temperature of City 1.
       sum1 = 0,    // for keeping the running total of the temperatures of City 1
       average1,    // for storing the average temperature of City 1.
       // Below variables are for City 2
       temp2,      
       highest2,
       lowest2,
       sum2 = 0,
       average2;

//    Pseudocode    
      
      while (!ifile.eof())
      {
            getline(ifile, city); 
             
            if (city == "City 1")
            {
                ifile >> temp1; 
                if (temp1 > highest1) 
                highest1 = temp1;
                if (temp1 < lowest1) 
                lowest1 = temp1;
                sum1 += temp1; 
                count1++;
            }
            else if (city == "City 2")
            {
                ifile >> temp2; 
                if (temp2 > highest2) 
                highest2 = temp2;
                if (temp2 < lowest2) 
                lowest2 = temp2;
                sum2 += temp2; 
                count2++; 
            }
      getline(ifile, city); 
      }
      average1 = sum1 / count1; 
      average2 = sum2 / count2; 
      
      cout << "City 1:" << endl; 
      cout << count1 << " " << " are recorded." << endl; 
      cout << fixed << setprecision(2) << "The average temperature is " << average1 << endl; 
      cout << fixed << setprecision(2) << "The highest temperature is " << highest1 << endl; 
      cout << fixed << setprecision(2) << "The lowest temperature is " << lowest1 << endl; 
      
      cout << "City 2:" << endl; 
      cout << count2 << " " << " are recorded." << endl; 
      cout << fixed << setprecision(2) << "The average temperature is " << average2 << endl; 
      cout << fixed << setprecision(2) << "The highest temperature is " << highest2 << endl;
      cout << fixed << setprecision(2) << "The lowest temperature is " << lowest2 << endl; 
      
}
Edit & run on cpp.sh

It works for temperature2.txt (below)
----------------------------------------------------
City 2
-25
City 1
-24
City 2
-23
City 1
-22
City 2
-21
City 1
-20
City 2
-19
City 1
-18
City 2
-17
City 1
-16
City 2
-15
City 1
-14
City 2
-13
City 1
-12
City 2
-11
City 1
-10
City 2
-9
City 1
-8
City 2
-7
City 1
-6
City 2
-5
City 1
-4
City 2
-3
City 1
-2
City 2
-1
City 1
0
City 2
1
City 1
2
City 2
3
City 1
4
City 2
5
City 1
6
City 2
7
City 1
8
City 2
9
----------------------------------------------------------
But the lowest value for City 2 in temperature1.txt (below) is incorrect for some reason, I get a gigantic number. (everything else is correct, including City 2 lowest in temperature2.txt)
------------------------------------------------------------
City 1
-20
City 2
-20
City 1
100
City 2
100
City 1
50
City 2
50
------------------------------------------------------------
Also how do I state the name of the file in the output? (Since it is out of scope).
Last edited on Mar 21, 2012 at 9:42pm
Mar 21, 2012 at 9:43pm
S G H (2638)

How do I state the name of the file in the output?
cout << fname;
or
cout << (fname.c_str());

Initialize your variables like this, so they will be handled properly:
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float temp1,
       highest1 = -65000.f,
       lowest1 = 65000.f,
       sum1 = 0.f,
       average1,
       temp2,
       highest2 = -65000.f,
       lowest2 = 65000.f,
       sum2 = 0.f,
       average2;
Mar 21, 2012 at 9:57pm
R N (15)
Instead of -6500.f I just initialized it to 0 and it worked. Your method seems a bit more complicated.

The only problem left: I cannot change the main function to display the name of the file so how would I display it in the 'process' function? (I am not allowed to change main function.)

These two lines work. 
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cout << count1 << " " << " are recorded." << endl; 
cout << count2 << " " << " are recorded." << endl;


These don't. 
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cout << count1 << " " << fname << " are recorded." << endl;
cout << count2 << " " << fname << " are recorded." << endl;
Last edited on Mar 21, 2012 at 10:02pm
Mar 21, 2012 at 10:04pm
S G H (2638)
Instead of -6500.f I just initialized it to 0 and it worked. Your method seems a bit more complicated.

If in your file you will never find values over 0, you will never record a max/min value.
Probably You Cannot on the fly.
Last edited on Mar 21, 2012 at 10:05pm
Mar 21, 2012 at 10:10pm
R N (15)
So is what does -65000.f and 65000.f mean? Does it mean the number of digits (65000 digits) of any number positive or negative?
Last edited on Mar 21, 2012 at 10:14pm
Mar 21, 2012 at 10:13pm
S G H (2638)
It means the lowest/highest float number that can be reached (It's not the lowest/highest float number, it's just approximative, but the lower/higher, the better, but be careful not to exceed)
Mar 21, 2012 at 10:15pm
R N (15)
If I changed my variables to doubles I would not need this right? (Just insert 6500. without f after .?) Since the default for floating point literals is double, not float.
Last edited on Mar 21, 2012 at 10:16pm
Mar 21, 2012 at 10:22pm
S G H (2638)
Yes. Since you are using integers in your code, you can check out for the lowest/highest value for an integer.
Lowest value, according to MSDN: –2147483647
Highest // // // // : 2147483647
Mar 21, 2012 at 10:43pm
R N (15)
Alright now this is my new code. 
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#include <iostream>
#include <fstream>
#include <string>
#include <iomanip>
using namespace std;
void process(ifstream & ifile); // Prototype
int main()
{
    string fname;
    ifstream ifile;
    char again;
    do
    {
        cout << "Enter the input filename: ";
        getline(cin, fname);
        ifile.open(fname.data());
        if (ifile)
        {
           cout << "**************************************************\n";
           process(ifile);
        }
        else
            cout << "Error opening " << fname << endl;
        ifile.close();
        ifile.clear();
        cout << "\nDo you want to process another file?(y/n) ";
        cin >> again;
        cin.ignore(80,'\n');
    } while (again == 'y' || again == 'Y');
    return 0;
}
void process(ifstream & ifile)
{
    string city;    // for reading in the city name
    int count1 = 0, // counts the number of temperature recorded for City 1.
        count2 = 0;
          
        // counts the number of temperature recorded for City 2/  
    double temp1,
       highest1 = -3.4E-38,
       lowest1 = 3.4E-38,
       sum1 = 0,
       average1,
       temp2,
       highest2 = -3.4E-38,
       lowest2 = 3.4E-38,
       sum2 = 0,
       average2;
   
      
      while (!ifile.eof())
      {
            getline(ifile, city); 
             
            if (city == "City 1")
            {
                ifile >> temp1; 
                if (temp1 > highest1) 
                highest1 = temp1;
                if (temp1 < lowest1) 
                lowest1 = temp1;
                sum1 += temp1; 
                count1++;
            }
            else if (city == "City 2")
            {
                ifile >> temp2; 
                if (temp2 > highest2) 
                highest2 = temp2;
                if (temp2 < lowest2) 
                lowest2 = temp2;
                sum2 += temp2; 
                count2++; 
            }
      getline(ifile, city); 
      }
      average1 = sum1 / count1; 
      average2 = sum2 / count2; 
      
      cout << "City 1:" << endl; 
      cout << count1 << " " << " are recorded." << endl; 
      cout << fixed << setprecision(2) << "The average temperature is " << average1 << endl; 
      cout << fixed << setprecision(2) << "The highest temperature is " << highest1 << endl; 
      cout << fixed << setprecision(2) << "The lowest temperature is " << lowest1 << endl; 
      
      cout << "City 2:" << endl; 
      cout << count2 << " " << " are recorded." << endl; 
      cout << fixed << setprecision(2) << "The average temperature is " << average2 << endl; 
      cout << fixed << setprecision(2) << "The highest temperature is " << highest2 << endl;
      cout << fixed << setprecision(2) << "The lowest temperature is " << lowest2 << endl; 
     
      
}
Edit & run on cpp.sh

I decided to stick the highest possible values for a double into the program (according to my textbook). These temperatures are not even physically feasible so I feel safe now.

I just have one more issue. I need to display the name of the file like this. 
Enter the input filename: temperature1.txt
**************************************************
City 1:
3 temperature1 are recorded.
The average temperature is 43.33
The highest temperature is 100.00
The lowest temperature is -20.00

City 2:
3 temperature1 are recorded.
The average temperature is 43.33
The highest temperature is 100.00
The lowest temperature is -20.00

Do you want to process another file?(y/n) y

I cannot change the main function in the process.
Like I said before.
These two lines work. (lines 81 and 87)

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cout << count1 << " " << " are recorded." << endl; 
cout << count2 << " " << " are recorded." << endl;


These don't. (replacements for lines 81 and 87)

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cout << count1 << " " << fname << " are recorded." << endl;
cout << count2 << " " << fname << " are recorded." << endl;


EDIT: Apparently I don't need to write the name of the file since it is pretty obvious what it is. Thanks for all the help guys.
Last edited on Mar 21, 2012 at 11:19pm
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