Computer Science Canada

numbers in a line
Author:  varundesi [ Mon Oct 30, 2006 2:11 pm ]
Post subject:  numbers in a line
Hi there, I need to write a program that reads up to 10 numbers per line to be stored in an array.The program calculates and displays the sum of the numbers, the mean (arithmetic average) of the numbers, and the largest and smallest values entered for each line.

the input file is

45 98 35 23 67 84
65 91 20 54 62 37 65 84 32
21 54 95 87 35 62 54 78
56
95 62 35 54 78


i have this much so far

c++:

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

int main()
{
    string sBuf;
    int nSum=0;
    double dMean=0;
    int nMin=999999;
    int nMax=0;
    int arnNums[10], nSize, i;
    ifstream fin("71dIN.txt");
    istringstream istr(sBuf); // open input array
    while(1)
    {
        getline(fin, sBuf);
        istr.clear();
        istr.str(sBuf);
        if(fin.eof()) break;
        i=0;
        while(1)
        {
            istr>>arnNums[i];
            i++;
            if(istr.eof()) break;
        }
        nSize = i;
        for(i = 0; i<nSize; i++)
        {
            if (arnNums[i]<nMin)
                nMin=arnNums[i];
            else if (arnNums[i]>nMax)
                nMax=arnNums[i];
            nSum+=arnNums[i];
            dMean=nSum/nSize;
        }
        cout<<nSum<<" ";
        cout<<dMean<<" ";
        cout<<nMin<<" ";
        cout<<nMax<<" ";
        cout<<endl;
        nSum=0;
    }
    return 0;
}


// The output i m getting is

352 58 23 98
510 56 20 98
486 60 20 98
56 56 20 98
324 64 20 98
Author:  Andy [ Mon Oct 30, 2006 4:45 pm ]
Post subject: 
so what's wrong with the output?
Author:  bugzpodder [ Mon Oct 30, 2006 4:46 pm ]
Post subject: 
reset min and max value after each dataset (try after output)
Author:  bugzpodder [ Mon Oct 30, 2006 4:48 pm ]
Post subject: 
also, you probably do not want to limit array of size to 10 (as any input larger than 10 would cause an overflow). Instead, you dont even need an array, as after a value was investigated there is no need to keep it around.
Author:  varundesi [ Mon Oct 30, 2006 5:20 pm ]
Post subject: 
Andy wrote:
so what's wrong with the output?


the min is wrong for line 3,4,5, and max is wrong for line 2,3,4,5.
Author:  varundesi [ Mon Oct 30, 2006 5:24 pm ]
Post subject: 
bugzpodder wrote:
reset min and max value after each dataset (try after output)


Thanks a lot man
that worked
Author:  wtd [ Mon Oct 30, 2006 5:39 pm ]
Post subject: 
I'm going to use this thread as a place to break the problem down, with little concern for the original solution. Understanding how to break a problem down into smaller problems is a more important lesson. Smile

So, one of the tiny little problems is getting all of the numbers from a string. Getting that string (a line from a file) in the first place is an entirely separate problem.

So... let's create a function:

code:
#include <vector>
#include <string>
#include <sstream>

std::vector<int> read_all_numbers_from_string(std::string s)
{
   std::istringstream buffer(s);
   int temporary_integer;

   std::vector<int> output;

   while (true)
   {
      buffer >> temporary_integer;
     
      if (buffer.fail())
      {
         break;
      }
      else
      {
         output.push_back(temporary_integer);
      }
   }

   return output;
}


However, with a little knowledge of the STL...

code:
#include <vector>
#include <string>
#include <sstream>
#include <algorithm>
#include <iterator>

std::vector<int> read_all_numbers_from_string(std::string s)
{
   std::istringstream buffer(s);
   std::vector<int> output;
   
   std::copy(std::istream_iterator<int>(buffer),
             std::istream_iterator<int>(),
             std::back_inserter(output));

   return output;
}


Either way, you now have this ability, and you know nothing is wrong with it. You can focus on other parts of the program. For instance, you'll probably want to write a function that can find the sum of a vector of ints. That'd be another small problem solved.

Why vectors at all?

Because there's no telling how many numbers a line will contain. Using an array in this situation makes little sense.
Author:  bugzpodder [ Tue Oct 31, 2006 8:12 am ]
Post subject: 
I am not a STL guru, but i think this works:

code:

while ( buffer >> temporary_integer)
       output.push_back(temporary_integer);
Author:  varundesi [ Tue Oct 31, 2006 2:48 pm ]
Post subject: 
Thanks for the info wtd, but i have no clue about STL's, thanks anyway.
Author:  wtd [ Tue Oct 31, 2006 3:41 pm ]
Post subject: 
The STL is the Standard Template Library. It is a huge part of the C++ standard library, and home to many powerful classes and functions, such as the vector class and copy function I used in that example, for instance.
Author:  wtd [ Tue Oct 31, 2006 5:35 pm ]
Post subject: 
A glimpse at the possibilities:

code:
#include <iostream>
#include <fstream>
#include <vector>
#include <algorithm>
#include <iterator>

#include "customized_line.h"

using namespace std;

int main()
{
   vector<customized_line<int> > lines;

   copy(istream_iterator<customized_line<int> >(cin),
        istream_iterator<customized_line<int> >(),
        back_inserter(lines));

   copy(lines.begin(), lines.end(),
        ostream_iterator<customized_line<int> >(cout, "\n"));
}
Author:  varundesi [ Thu Nov 02, 2006 8:14 pm ]
Post subject: 
wtd wrote:
A glimpse at the possibilities:

code:
#include <iostream>
#include <fstream>
#include <vector>
#include <algorithm>
#include <iterator>

#include "customized_line.h"

using namespace std;

int main()
{
   vector<customized_line<int> > lines;

   copy(istream_iterator<customized_line<int> >(cin),
        istream_iterator<customized_line<int> >(),
        back_inserter(lines));

   copy(lines.begin(), lines.end(),
        ostream_iterator<customized_line<int> >(cout, "\n"));
}


looks like a linux file, (jar.gz)
thanks
Author:  Andy [ Thu Nov 02, 2006 10:33 pm ]
Post subject: 
err no.. that's a archive that can be opened with a variety of decompression programs
Author:  md [ Thu Nov 02, 2006 11:31 pm ]
Post subject: 
it's a gzip'd tar archive. It's a standard that's been around for oh, 20 years? Any decent compression program shoudl be able to decompress it for you.
Author:  Andy [ Fri Nov 03, 2006 12:08 am ]
Post subject: 
and fyi, winzip is NOT a decent compression program
Author:  Null [ Fri Nov 03, 2006 6:32 pm ]
Post subject: 
wtd, you know those std::string's should be passed in as const references...
Author:  wtd [ Fri Nov 03, 2006 7:16 pm ]
Post subject: 
Null wrote:
wtd, you know those std::string's should be passed in as const references...


Refresh my memory... which strings?
Author:  Null [ Fri Nov 03, 2006 10:42 pm ]
Post subject: 
code:

#include <vector>
#include <string>
#include <sstream>

std::vector<int> read_all_numbers_from_string(std::string s)
{
   std::istringstream buffer(s);
   int temporary_integer;

   std::vector<int> output;

   while (true)
   {
      buffer >> temporary_integer;
     
      if (buffer.fail())
      {
         break;
      }
      else
      {
         output.push_back(temporary_integer);
      }
   }

   return output;
}
Author:  wtd [ Fri Nov 03, 2006 10:54 pm ]
Post subject: 
Ah. I thought you were referring to my STL-exploiting code. Smile
Author:  md [ Fri Nov 03, 2006 10:59 pm ]
Post subject: 
Null wrote:
wtd, you know those std::string's should be passed in as const references...


For all you know the data is stored as the same copy and is just a reference internally, the STL does not specify that it can't be Wink
Author:  wtd [ Fri Nov 03, 2006 11:07 pm ]
Post subject: 
md wrote:
Null wrote:
wtd, you know those std::string's should be passed in as const references...


For all you know the data is stored as the same copy and is just a reference internally, the STL does not specify that it can't be Wink


Three words: Copy. On. Write. Smile

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