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Sorting an array of doubles?

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Join Date: Jul 2008

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java_girl

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Sorting an array of doubles?

Jul 9th, 2008

Hi.

The objective is to sort an array of doubles. My effort is listed below:

 Help with Code Tags 
 C Syntax (Toggle Plain Text) 
#include <stdio.h>
#define MAX 10
 
void sort( double* n[], int q );
void print_nums( double* n[], int q );
 
int main( void ) {
 
   double* nums[MAX];
   int i; 
 
   for( i = 0; i < MAX; i++ ) {
      printf( "Please enter a double variable: " );
      scanf( "%f", &nums[i] );
   }
 
   sort( nums, 10 );
   print_nums( nums, 10 ); 
 
   return 0;
}
 
void sort( double* n[], int q ) {
 
   int a, b;
 
   double* x;
 
   for( a = 1; a < q; a++ ) {
      for( b = 0; b < q - 1; b++ ) {
         if( n[b] > n[b + 1] ) {
            x = n[ b ];
            n[b] = n[b + 1];
            n[b + 1] = x;
         }
      }
   }
}
 
void print_nums( double* n[], int q ) {
 
   int count;
 
   for( count = 0; count < q; count++ )
      printf( "\n%f", n[count] );
}
#include <stdio.h>
#define MAX 10

void sort( double* n[], int q );
void print_nums( double* n[], int q );

int main( void ) {

   double* nums[MAX];
   int i; 

   for( i = 0; i < MAX; i++ ) {
      printf( "Please enter a double variable: " );
      scanf( "%f", &nums[i] );
   }

   sort( nums, 10 );
   print_nums( nums, 10 ); 

   return 0;
}

void sort( double* n[], int q ) {

   int a, b;

   double* x;

   for( a = 1; a < q; a++ ) {
      for( b = 0; b < q - 1; b++ ) {
         if( n[b] > n[b + 1] ) {
            x = n[ b ];
            n[b] = n[b + 1];
            n[b + 1] = x;
         }
      }
   }
}

void print_nums( double* n[], int q ) {

   int count;

   for( count = 0; count < q; count++ )
      printf( "\n%f", n[count] );
}

The output I'm seeing is as follows:

 Help with Code Tags 
 C Syntax (Toggle Plain Text) 
Please enter a double variable: 2.2
Please enter a double variable: 2.2
Please enter a double variable: 2.1
Please enter a double variable: 2.12
Please enter a double variable: 333.2
Please enter a double variable: 332.22
Please enter a double variable: 1.1
Please enter a double variable: 2.21
Please enter a double variable: 2.122
Please enter a double variable: 2.122
 
2.800000
2.800000
2.800000
2.800000
2.800000
2.800000
2.800000
2.800000
2.800000
2.800000
Please enter a double variable: 2.2
Please enter a double variable: 2.2
Please enter a double variable: 2.1
Please enter a double variable: 2.12
Please enter a double variable: 333.2
Please enter a double variable: 332.22
Please enter a double variable: 1.1
Please enter a double variable: 2.21
Please enter a double variable: 2.122
Please enter a double variable: 2.122

2.800000
2.800000
2.800000
2.800000
2.800000
2.800000
2.800000
2.800000
2.800000
2.800000

Thanks,

Molly

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Join Date: Apr 2004

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Dave Sinkula Dave Sinkula is offline

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Re: Sorting an array of doubles?

Jul 9th, 2008

Use %lf with scanf for type double .

[edit]But there are a number of indirection issues as well...

Last edited by Dave Sinkula; Jul 9th, 2008 at 10:14 pm.

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Join Date: Apr 2004

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Re: Sorting an array of doubles?

Jul 9th, 2008

You have too much indirection.

Help with Code Tags

(Toggle Plain Text)

#include <stdio.h>
#define MAX 10

void sort( double* n, int q );
void print_nums( double* n, int q );

int main( void ) {

   double nums[MAX];
   int i;

   for( i = 0; i < MAX; i++ ) {
      printf( "Please enter a double variable: " );
      scanf( "%lf", &nums[i] );
   }

   sort( nums, 10 );
   print_nums( nums, 10 );

   return 0;
}

void sort( double* n, int q ) {

   int a, b;

   double x;

   for( a = 1; a < q; a++ ) {
      for( b = 0; b < q - 1; b++ ) {
         if( n[b] > n[b + 1] ) {
            x = n[ b ];
            n[b] = n[b + 1];
            n[b + 1] = x;
         }
      }
   }
}

void print_nums( double* n, int q ) {

   int count;

   for( count = 0; count < q; count++ )
      printf( "\n%f", n[count] );
}

Last edited by Dave Sinkula; Jul 9th, 2008 at 10:22 pm.

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Join Date: Jul 2008

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java_girl

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Re: Sorting an array of doubles?

Jul 10th, 2008

Thanks for the help Dave.

Looking at the initial exercise, it reads:

Write a program that uses pointers to type double variables to accept 10 numbers from the user, sort them, and print them to the screen.

 Help with Code Tags 
 C Syntax (Toggle Plain Text) 
double* n[]
double* n[]

uses double indirection? If so, can you explain? I assumed it translated to:

'n' is an array (unspecified length) of pointers to type double.

Thanks,

Molly

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Re: Sorting an array of doubles?

Jul 10th, 2008

•

Originally Posted by java_girl

Help with Code Tags

C Syntax (Toggle Plain Text)
double* n[]
double* n[]
uses double indirection? If so, can you explain? I assumed it translated to:

'n' is an array (unspecified length) of pointers to type double.

Not in a function prototype -- there it is a pointer to a pointer to double. You may want to peruse the earlier c-faq.com link again.

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ssharish2005 ssharish2005 is offline

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Re: Sorting an array of doubles?

Jul 10th, 2008

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Write a program that uses pointers to type double variables to accept 10 numbers from the user, sort them, and print them to the screen.

This is pretty tricky. The question says "pointers to type double variable", but it don't anywhere say "pointers to type double array. Which is what is this

 Help with Code Tags 
 C Syntax (Toggle Plain Text) 
double *n[];
double *n[];

That is totally wrong. That a pointer to a pointer. Well let me give you an example. With the above notation what you could do is this

 Help with Code Tags 
 C Syntax (Toggle Plain Text) 
double arr1[] = { 20.5, 3.6, 452.3, 6.2, 4.25 };
double arr2[] = { 40.5, 3.5, 42.3, 6.2006, 45.25 };
 
double *array[10];
 
array[0] = arr1;
array[1] = arr2;
.
.
double arr1[] = { 20.5, 3.6, 452.3, 6.2, 4.25 };
double arr2[] = { 40.5, 3.5, 42.3, 6.2006, 45.25 };
       
double *array[10];

array[0] = arr1;
array[1] = arr2;
.
.

As you can the each elements of array hold an starting address of an array of doubles. If you are trying to sort that sort of an array its completely a different approach. You got to do more than what sort methods you have followed. You should consult your professor to make sure what he is expecting.

Well, at least i understand that from the question. Please correct if am wrong.

ssharish.

Last edited by ssharish2005; Jul 10th, 2008 at 12:51 pm.