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Join Date: Feb 2008

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demroth

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sorting problem

Mar 30th, 2008

I thought I had posted this earlier but...
I am working on a sorting problem using counting sort but am getting a crash when I run the program. I have fixed some of the problems but I am still missing something. I just need a extra pair of eyes to find the rest.

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#include <cstdlib>
#include <iostream>
#include <fstream>
 
 
using namespace std;
void countSort(int nums[], int size);
 
int main()
{
  int i;
  char filename[50];
  int arraysize = 8; //the size of the array with all of its elements;
  int numbers[8]; //the number of elements in the array
  ifstream infile;
 
 
  cout<<"Enter the name of the file you wish to open "<<endl;
  cin>>filename; 
 
  infile.open(filename); //open the input file
  if(!infile.is_open()) //if the input file does not open
  {
    cout<<"Could not open the file "<<filename<<" The program will now close."<<endl;
    exit(EXIT_FAILURE); //exit the program
  }
 
  while(infile.good()) //if the file opens
  {
      for(i = 0; i <= arraysize; i++) //read all of the integers from the file...
          infile >> numbers[i]; //..into the array, numbers
  }
 
  countSort(numbers, arraysize);
 
 for(i = 0; i <= arraysize; i++)
   cout << numbers[i] << endl; //prints out the numbers to the console
 
 infile.close(); //close input file
 system("PAUSE");
 return EXIT_SUCCESS; //exit the program
}
 
void countSort(int numbers[], int size)
{
     int i, counter, j;
     int min = numbers[0];
     int max = min;  
     int a[8], b[8], c[max];
 
   for(i = 0; i <= size; i++)
   { 
     if(numbers[i] < min)
       min = numbers[i];
     else if(numbers[i] > max)
       max = numbers[i];
   }    
     for(i = 0; i <= max; i++)
        c[i] = 0;
     for(j = 0; j <= 8; j++)
       c[a[j]] = c[a[j]] + 1;
     for(i = 0; i <= max; i++)
       c[i] = c[i] + c[i - 1];
     for(j = 0; j <= 8; j--)
     {
       b[c[a[j]]] = a[j];
       c[a[j]] = c[a[j]] -1;
     }
 
}
#include <cstdlib>
#include <iostream>
#include <fstream>


using namespace std;
void countSort(int nums[], int size);

int main()
{
  int i;
  char filename[50];
  int arraysize = 8; //the size of the array with all of its elements;
  int numbers[8]; //the number of elements in the array
  ifstream infile;
  
  
  cout<<"Enter the name of the file you wish to open "<<endl;
  cin>>filename; 
  
  infile.open(filename); //open the input file
  if(!infile.is_open()) //if the input file does not open
  {
    cout<<"Could not open the file "<<filename<<" The program will now close."<<endl;
    exit(EXIT_FAILURE); //exit the program
  }
  
  while(infile.good()) //if the file opens
  {
      for(i = 0; i <= arraysize; i++) //read all of the integers from the file...
          infile >> numbers[i]; //..into the array, numbers
  }
  
  countSort(numbers, arraysize);
 
 for(i = 0; i <= arraysize; i++)
   cout << numbers[i] << endl; //prints out the numbers to the console
   
 infile.close(); //close input file
 system("PAUSE");
 return EXIT_SUCCESS; //exit the program
}
  
void countSort(int numbers[], int size)
{
     int i, counter, j;
     int min = numbers[0];
     int max = min;  
     int a[8], b[8], c[max];
   
   for(i = 0; i <= size; i++)
   { 
     if(numbers[i] < min)
       min = numbers[i];
     else if(numbers[i] > max)
       max = numbers[i];
   }    
     for(i = 0; i <= max; i++)
        c[i] = 0;
     for(j = 0; j <= 8; j++)
       c[a[j]] = c[a[j]] + 1;
     for(i = 0; i <= max; i++)
       c[i] = c[i] + c[i - 1];
     for(j = 0; j <= 8; j--)
     {
       b[c[a[j]]] = a[j];
       c[a[j]] = c[a[j]] -1;
     }
  
}

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Re: sorting problem

Mar 30th, 2008

The loop at lines 28-32 could be better written like this:

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int i = 0;
while( i < arraysize && infile >> numbers[i] )
{
    i++;
}
int i = 0;
while( i < arraysize && infile >> numbers[i] )
{
    i++;
}

line 34: do you know for a fact that the file contains exactly 8 integers? It would be better to pass the value of i from the above code
countSort(numbers, i);
line 51: >> for(i = 0; i <= size; i++)
You need to use the < operator, not <= because arrays are counted 0 to but not include the number of elements in the array -- 8 in this program. Same thing goes for all the other loops in that function. They all count beyond the legal array bounds.

Last edited by Ancient Dragon; Mar 30th, 2008 at 8:43 pm.

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Join Date: Feb 2008

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demroth

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Re: sorting problem

Mar 30th, 2008

The program is suppose to read in a single file that will have between 8 to 256 integers. Since I am not yet familiar with vectors and dynamic arrays, I am only creating the program to read only the first file which will have 8 integers. This is just part of the learning curve for me.

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Re: sorting problem

Mar 30th, 2008

That's ok but you still can not count from 0 to and including 8. If you do that is 9 numbers, not 8. If you are required to read a max of 256 integers then set the array size fo the max of 256.

and use the const arraysize declared on line 13 to declare the array on line 14.

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demroth

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Re: sorting problem

Mar 30th, 2008

Ok, I have made the changes but I still get a crash when running the program.

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
#include <cstdlib>
#include <iostream>
#include <fstream>
 
 
using namespace std;
void countSort(int nums[], int size);
 
int main()
{
 
  char filename[50];
  const int arraysize = 256; //the size of the array with all of its elements;
  int numbers[arraysize]; //the number of elements in the array
  ifstream infile;
 
 
  cout<<"Enter the name of the file you wish to open "<<endl;
  cin>>filename; 
 
  infile.open(filename); //open the input file
  if(!infile.is_open()) //if the input file does not open
  {
    cout<<"Could not open the file "<<filename<<" The program will now close."<<endl;
    exit(EXIT_FAILURE); //exit the program
  }
 
 int i = 0;
 while( i < arraysize && infile >> numbers[i] )
 {
    i++;
 }
 
 
  countSort(numbers, i);
 
 for(i = 0; i < arraysize; i++)
   cout << numbers[i] << endl; //prints out the numbers to the console
 
 infile.close(); //close input file
 system("PAUSE");
 return EXIT_SUCCESS; //exit the program
}
 
void countSort(int numbers[], int size)
{
     int i, counter, j;
     int min = numbers[0];
     int max = min;  
     int a[8], b[8], c[max];
 
   for(i = 0; i < size; i++)
   { 
     if(numbers[i] < min)
       min = numbers[i];
     else if(numbers[i] > max)
       max = numbers[i];
   }    
     for(i = 0; i < max; i++)
        c[i] = 0;
     for(j = 0; j < 8; j++)
       c[a[j]] = c[a[j]] + 1;
     for(i = 0; i < max; i++)
       c[i] = c[i] + c[i - 1];
     for(j = 0; j < 8; j--)
     {
       b[c[a[j]]] = a[j];
       c[a[j]] = c[a[j]] -1;
     }
 
}
#include <cstdlib>
#include <iostream>
#include <fstream>


using namespace std;
void countSort(int nums[], int size);

int main()
{
 
  char filename[50];
  const int arraysize = 256; //the size of the array with all of its elements;
  int numbers[arraysize]; //the number of elements in the array
  ifstream infile;
  
  
  cout<<"Enter the name of the file you wish to open "<<endl;
  cin>>filename; 
  
  infile.open(filename); //open the input file
  if(!infile.is_open()) //if the input file does not open
  {
    cout<<"Could not open the file "<<filename<<" The program will now close."<<endl;
    exit(EXIT_FAILURE); //exit the program
  }
  
 int i = 0;
 while( i < arraysize && infile >> numbers[i] )
 {
    i++;
 }

  
  countSort(numbers, i);
 
 for(i = 0; i < arraysize; i++)
   cout << numbers[i] << endl; //prints out the numbers to the console
   
 infile.close(); //close input file
 system("PAUSE");
 return EXIT_SUCCESS; //exit the program
}
  
void countSort(int numbers[], int size)
{
     int i, counter, j;
     int min = numbers[0];
     int max = min;  
     int a[8], b[8], c[max];
   
   for(i = 0; i < size; i++)
   { 
     if(numbers[i] < min)
       min = numbers[i];
     else if(numbers[i] > max)
       max = numbers[i];
   }    
     for(i = 0; i < max; i++)
        c[i] = 0;
     for(j = 0; j < 8; j++)
       c[a[j]] = c[a[j]] + 1;
     for(i = 0; i < max; i++)
       c[i] = c[i] + c[i - 1];
     for(j = 0; j < 8; j--)
     {
       b[c[a[j]]] = a[j];
       c[a[j]] = c[a[j]] -1;
     }
  
}

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Re: sorting problem

Mar 30th, 2008

>>Ok, I have made the changes but I still get a crash when running the program.

I'm not supprised because there are compile errors you have to fix.
line 50: you can't allocate an array using an int that is not a const. The way to allocate c is using the new operator
int* c = new int[max];
lines 59-69: you are still using the hard-coded value of 8 where you should be using size.

line 62: using unitialized array a, which is the reason your program crashes.

Last edited by Ancient Dragon; Mar 30th, 2008 at 9:30 pm.

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Jacky1

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Re: sorting problem

Mar 30th, 2008

I think it's still crashing

0x08048fbb in countSort (numbers=0xbfea2af0, size=5) at sorting.cpp:69
69 b[c[a[j]]-1] = a[j];

I wish I can help

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Re: sorting problem

Mar 30th, 2008

•

Originally Posted by Jacky1

I think it's still crashing

0x08048fbb in countSort (numbers=0xbfea2af0, size=5) at sorting.cpp:69
69 b[c[a[j]]-1] = a[j];

I wish I can help

Its because the values in array a are trashed -- it was never initialized to anything.

Don't PM me with questions -- you might get a nasty PM in response. If you have a question then post it in one of the forums.

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demroth

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Re: sorting problem

Mar 30th, 2008

Here is the modified code. I am still working on the crash.

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
#include <cstdlib>
#include <iostream>
#include <fstream>
 
 
using namespace std;
void countSort(int nums[], int size);
 
int main()
{
 
  char filename[50];
  const int arraysize = 8; //the size of the array with all of its elements;
  int numbers[arraysize]; //the number of elements in the array
  ifstream infile;
 
 
  cout<<"Enter the name of the file you wish to open "<<endl;
  cin>>filename; 
 
  infile.open(filename); //open the input file
  if(!infile.is_open()) //if the input file does not open
  {
    cout<<"Could not open the file "<<filename<<" The program will now close."<<endl;
    exit(EXIT_FAILURE); //exit the program
  }
 
 int i = 0;
 while( i < arraysize && infile >> numbers[i] )
 {
    i++;
 }
 
 
  countSort(numbers, i);
 
 for(i = 0; i < arraysize; i++)
   cout << numbers[i] << endl; //prints out the numbers to the console
 
 infile.close(); //close input file
 system("PAUSE");
 return EXIT_SUCCESS; //exit the program
}
 
void countSort(int numbers[], int size)
{
     int i, counter, j;
     int min = numbers[0];
     int max = min;  
     int a[size], b[size];
     int* c = new int[max];
 
   for(i = 0; i < size; i++)
   { 
     if(numbers[i] < min)
       min = numbers[i];
     else if(numbers[i] > max)
       max = numbers[i];
   }    
     for(i = 0; i < max; i++)
        c[i] = 0;
     for(j = 0; j < size; j++)
       c[a[j]] = c[a[j]] + 1;
     for(i = 0; i < max; i++)
       c[i] = c[i] + c[i - 1];
     for(j = 0; j < size; j--)
     {
       b[c[a[j]]] = a[j];
       c[a[j]] = c[a[j]] -1;
     }
 delete[] c; 
}
#include <cstdlib>
#include <iostream>
#include <fstream>


using namespace std;
void countSort(int nums[], int size);

int main()
{
 
  char filename[50];
  const int arraysize = 8; //the size of the array with all of its elements;
  int numbers[arraysize]; //the number of elements in the array
  ifstream infile;
  
  
  cout<<"Enter the name of the file you wish to open "<<endl;
  cin>>filename; 
  
  infile.open(filename); //open the input file
  if(!infile.is_open()) //if the input file does not open
  {
    cout<<"Could not open the file "<<filename<<" The program will now close."<<endl;
    exit(EXIT_FAILURE); //exit the program
  }
  
 int i = 0;
 while( i < arraysize && infile >> numbers[i] )
 {
    i++;
 }

  
  countSort(numbers, i);
 
 for(i = 0; i < arraysize; i++)
   cout << numbers[i] << endl; //prints out the numbers to the console
   
 infile.close(); //close input file
 system("PAUSE");
 return EXIT_SUCCESS; //exit the program
}
  
void countSort(int numbers[], int size)
{
     int i, counter, j;
     int min = numbers[0];
     int max = min;  
     int a[size], b[size];
     int* c = new int[max];
   
   for(i = 0; i < size; i++)
   { 
     if(numbers[i] < min)
       min = numbers[i];
     else if(numbers[i] > max)
       max = numbers[i];
   }    
     for(i = 0; i < max; i++)
        c[i] = 0;
     for(j = 0; j < size; j++)
       c[a[j]] = c[a[j]] + 1;
     for(i = 0; i < max; i++)
       c[i] = c[i] + c[i - 1];
     for(j = 0; j < size; j--)
     {
       b[c[a[j]]] = a[j];
       c[a[j]] = c[a[j]] -1;
     }
 delete[] c; 
}