float arrays question

justachessgame · #1 08-Nov-2004, 16:13

I am having problems writing this code. I have to write a program that declares a float array with 100 elements and also:

1. displays the sum of the elements in the array
2. displays the smallest number in the array
3. displays the 5 largest numbers in the array

If anyone could provide me with a little (or a lot) of help I would appreciate it! Please...

This is the beginning that I have so far...

CPP / C++ / C Code:

#include <stdio.h>

int x = 100;
int main()
{
	x = 100;
	printf( "x = %d\n", x );
	float x[100];
	
	return 0;
}

justachessgame · #2 08-Nov-2004, 17:20

OK...I have created a program but it does not do what I want it to do..I am only able to find the greatest of three numbers...how do I get five?

Here is what I have since my last post...

CPP / C++ / C Code:

#include <stdio.h>

int main()
{
    int x, y, z, max;
    
	
    printf ( "Enter a number " ); //Evaluates first number
    scanf ( "%d" , &x);
	printf ( "Enter a number " ); //Evaluates second number
    scanf ( "%d" , &y);
	printf ( "Enter a number " ); //Evaluates third number
    scanf ( "%d" , &z);

    if( x > y )
		max = x;
	else
		max = y;
	if( x < z )
		max = z;
	
	
		
	printf( "The greatest value is %d", max ); //Finds the greatest number of three not five like I need.
	
	  
    return (0);

davekw7x · #3 08-Nov-2004, 18:06

Quote:

Originally Posted by justachessgame

I am having problems writing this code. I have to write a program that declares a float array with 100 elements and also:

1. displays the sum of the elements in the array
2. displays the smallest number in the array
3. displays the 5 largest numbers in the array

If anyone could provide me with a little (or a lot) of help I would appreciate it! Please...

This is the beginning that I have so far...

CPP / C++ / C Code:

#include <stdio.h>

int x = 100;
int main()
{
	x = 100;
	printf( "x = %d\n", x );
	float x[100];
	
	return 0;
}

I don't understand your declarations for int x. You want float x[100].

I'll get you started:

First of all in order to test the code, you have to put something into the array.

I will fill the array with random numbers between 0 and 1. Maybe you want some other function to put some values in the array, since with random values, how will you know you have the right answer? For example you could simply set ary[i] = (float)i in your fill_array() function. Whatever.

Here's a thought: start with an array, say of 10 elements and initialize it with some specific values. Then print out all of the values, and see if your functions are working properly on them. Just a thought.

Here's a start:

CPP / C++ / C Code:

#include <stdio.h>
#include <stdlib.h>

int main()
{
  void fill_array(float *, int);
  float sum_array(float *, int);
  float smallest_in_array(float *, int);
  void  find_smallest_five(float *, float *);
  float x[100];

  fill_array(x, 100);
  
  return 0;
}

void fill_array(float *ary, int size)
{
  int i;
  for (i = 0; i < size; i++) {
    ary[i] = (float)rand()/(float)RAND_MAX;
  }
}

Now, you must make functions that step through the array that

1. add the elements and return the value in function sum_array().

2. find the smallest element in the array and return its value in function smallest_in_array().

3. find the smallest five elements and return them somehow. Do the first two things and save this for last.

Regards,

Dave

justachessgame · #4 08-Nov-2004, 18:12

Quote:

Originally Posted by davekw7x

I don't understand your declarations for int x. You want float x[100].

I'll get you started:

First of all in order to test the code, you have to put something into the array.

I will fill the array with random numbers between 0 and 1. Maybe you want some other function to put some values in the array, since with random values, how will you know you have the right answer? For example you could simply set ary[i] = (float)i in your fill_array() function. Whatever.

Here's a thought: start with an array, say of 10 elements and initialize it with some specific values. Then print out all of the values, and see if your functions are working properly on them. Just a thought.

Here's a start:

CPP / C++ / C Code:

#include <stdio.h>
#include <stdlib.h>

int main()
{
  void fill_array(float *, int);
  float sum_array(float *, int);
  float smallest_in_array(float *, int);
  void  find_smallest_five(float *, float *);
  float x[100];

  fill_array(x, 100);
  
  return 0;
}

void fill_array(float *ary, int size)
{
  int i;
  for (i = 0; i < size; i++) {
    ary[i] = (float)rand()/(float)RAND_MAX;
  }
}

Now, you must make functions that step through the array that

1. add the elements and return the value in function sum_array().

2. find the smallest element in the array and return its value in function smallest_in_array().

3. find the smallest five elements and return them somehow. Do the first two things and save this for last.

Regards,

Dave

I see what you are saying Dave...but I really don't understand how to get 100 or even 10 elements to output randomly. I know that I have to use srand but how do I format it? By the way...thank you for replying to my message.

davekw7x · #5 08-Nov-2004, 18:17

Quote:

Originally Posted by justachessgame

I see what you are saying Dave...but I really don't understand how to get 100 or even 10 elements to output randomly. I know that I have to use srand but how do I format it? By the way...thank you for replying to my message.

OK. Here's a test case with 10 elements:

CPP / C++ / C Code:

#include <stdio.h>
#include <stdlib.h>


int main()
{
  void fill_array(float *, int);
  float sum_array(float *, int);
  float smallest_in_array(float *, int);
  void  find_smallest_five(float *, float *);
  float x[10];

  int i;

  fill_array(x, 10);

  for (i = 0; i < 10; i++) {
    printf("x[%d] = %f\n", i, x[i]);
  }
  
  return 0;
}

void fill_array(float *ary, int size)
{
  int i;
  for (i = 0; i < size; i++) {
    ary[i] = (float)rand()/(float)RAND_MAX;
  }
}

A note: I filled the array by calling rand() a number of times. Since I didn't use srand() to seed the random number generator, you will get the same numbers every time you run the program. That makes it easier to debug (at least it does for me). If you would rather initialize the array with specific numbers, then throw away everything associated with fill_array(), change this in main:

change this

CPP / C++ / C Code:

float x[10];

to something like this

CPP / C++ / C Code:

float x[10] = {1.2, 33.0, -99.0, 0.123, -1.222, 5.0, 89.999, 23.0, 0.0, 622441.0};

Now, it's your turn.

Regards,

Dave

justachessgame · #6 08-Nov-2004, 18:18

OK...this generates 100 random numbers...but chooses the second largest. How do I make it choose the 5 largest?

CPP / C++ / C Code:

#include <stdio.h>
#include <stdlib.h>
#include <time.h>

int main()
{
	int s, t;
	int max;
	int max2;
	int x[100];
	int temp;
	
	// Create and initialize array
	srand( time( NULL ) ); // seed random number generator

	for( t = 0; t < 100; t = t + 1 )
	{
		x[t] = rand() % 100;
	}
	
	//check for the max
	max = x[0] ;
	for( t = 1; t < 100; t++ )
	{
	   if( x[t] >= max )
	   {
  	  	  max = x[t];
   	   }
    }

	//check for max2
	max2 = x[0] ;
	for( t = 1; t < 100; t++ )
	{
	   if( x[t] >= max2 && x[t] < max )
	   {
  	  	  max2 = x[t];
   	   }
    }

	// display array contents
	for( t = 0; t < 100; t++ )
	{
	   printf( "%d ", x[t] ); 	  
	}
	
	//display current max
    printf ( "\n" ) ;
	printf ( "max = %d\n", max );
		
	
	printf( "The second largest number is %d\n", max2 );

    
	return 0;
}

nkhambal · #7 08-Nov-2004, 20:37

Following is one way to find 5 largest numbers in set of 100 numbers.

CPP / C++ / C Code:

int mx1,mx2,mx3,mx4,mx5;      //5 variables to hold 5 max numbers

mx1=mx2=mx3=mx4=mx5=0;	//Initialize all maximum numbers to 0.

  for( t =0; t < 100; t++)
  {
			if (!(x[t]==mx1) && !(x[t]==mx2) && !(x[t]==mx3) && !(x[t]==mx4) && !(x[t]==mx5)) //Avoid Duplicate numbers
			{
			
				if(x[t]>mx1)
				 {
					 mx5=mx4;
					 mx4=mx3;
					 mx3=mx2;
					 mx2=mx1;
					 mx1=x[t];
				 } else if (x[t]>mx2)
				 {
					mx5=mx4;
					mx4=mx3;
					mx3=mx2;
					mx2=x[t];
				 } else if (x[t]>mx3)
				 {
					mx5=mx4;
					mx4=mx3;
					mx3=x[t];
				 } else if (x[t]>mx4)
				 {
					 mx5=mx4;
					 mx4=x[t];
				 } else if (x[t]>mx5)
				 {
					mx5=x[t];
				 }
			 }
}

printf ( "\n5 Maximum numbers are\n" ) ;
  printf ( "mx1:= %d  mx2:= %d  mx3:=%d  mx4:=%d  mx5:=%d \n", mx1,mx2,mx3,mx4,mx5 );

This is just one way. Someone might come up with more efficient way to do it.

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