Thread: Help with basic program

Hello,
I am trying to write a program where you enter an undefined amount of numbers and when you type in -1 it will output the average of the numbers you have entered. I am having trouble figuring out how to keep storing a new number. I figure I need a variable for the amount of numbers entered, and one for each of the numbers entered but it has to be unlimited.
Here is what i have so far and I don't know if I have the right idea. it doesnt work and when I run it I get runtime errors.

Code:

#include <stdio.h>
#include <math.h>

int main(void)
{
	int n,newnumber,average,count=0,total;
	printf("enter numbers: \n");
	while (n != -1, newnumber != -1)
	{
	scanf_s("%lf",&n);
	scanf_s("%lf",&newnumber);
	total=n+newnumber;
	count++;
	}
	if (n==-1,newnumber==-1)
	average=total/count;
	printf("average is: %i",average);
getchar();
return 0;
}

Instead of keeping track of each number entered, just keep track of a running sum:

Code:

sum = 0
numbers_entered = 0
loop until input number is -1
{
  input number from user
  if number is not -1
  {
    add number to sum
    increment numbers_entered
  }
}
print sum divided by numbers_entered

Hi,
well I am stuck on one more problem. I have to read a text file numbers.txt and list how many even numbers there are in the file. I think I might be over complicating things again everything comes out fine except the for (even_test=0) says i need ; before ) i tried a lot of things but i think if I can get that line working my code would be fine.
I would really appreciate any help,
Thank you
(the numbers.txt is just a plain list of random numbers no order)

Code:

#include <stdio.h>
#include <math.h>
#define FILENAME "numbers.txt"
int main (void)
{
	/* Declare variables */
	int file_numbers,number_even,num_data,even_test;
	number_even = 0;
	FILE *numbers;
	/* read numbers.txt file */
	numbers = fopen(FILENAME,"r");
	while ((fscanf(numbers,"%lf",&file_numbers)) == 2)
	{
		num_data++;
		if (num_data == 1)
		{
			even_test = file_numbers%2;
		}
			for (even_test; even_test=0; number_even++)
		
	
	printf("the amount of even numbers are: %i",number_even);
	}
        getchar();
	getchar();
	return 0;
}

Here is an update of what ive changed, still having problems hopefully im getting closer!

Code:

#include <stdio.h>
#include <math.h>
#define FILENAME "numbers.txt"
int main (void)
{
	/* Declare variables */
	int file_numbers,number_even,even_test;
	number_even = 0;
	FILE *numbers;
	/* read numbers.txt file */
	numbers = fopen(FILENAME,"r");
	while ((fscanf(numbers,"%lf",&file_numbers)) == 2)
	{
			even_test = file_numbers%2;
		
			if (even_test = 0)
			
				number_even++;
						
			
		
	}
	printf("the amount of even numbers are: %i",number_even);
	getchar();
	getchar();
	return 0;
		
}

I'm not sure what your goal is with num_data. You're on the right track with the % operator, but for loops are designed for... looping. I believe you want something more like:

Code:

if(even_test)
{
    // Increment the even number counter
}

No looping necessary. Also, your printf statement should be after the while loop if you want to display the total after reading the entire file.

[QUOTE=brettski900;1007478]

Code:

if (even_test == 0)

Add another = sign in that if check. A single = is for assigning, a double == is for testing equality. The way you had it, the if check always sets even_test to zero and never enters the body of the if statement.

Thank you guys so much i took your advice and i made the program work! here it is for future reference.

Code:

#include <stdio.h>
#include <math.h>
/* define the file */
#define FILENAME "numbers.txt"
int main (void)
{
	/* Declare variables */
	int file_numbers,number_even,even_test;
	/* set number_even to 0 */
	number_even = 0;
	/* FILE is set to numbers */
	FILE *numbers;
	/* read numbers.txt file */
	numbers = fopen(FILENAME,"r");
	/* Loop read data if the function is read it will have a value of 1 
	   if it does not have a value of 1, end loop*/
	while ((fscanf(numbers,"%d",&file_numbers)) == 1)
	{
			/* divide the file_numbers by 2 */
			even_test = file_numbers%2;
			/* if the remainder is 0 then the number is even! */
			if (even_test == 0)
			/* add 1 to number_even */
			number_even++;						
					
	}
	/* print the number_even which will display the amount of even numbers */
	printf("the amount of even numbers are: %i",number_even);
	getchar();
	getchar();
	return 0;
		
}

Thanks again!
Brett