Thread: basic printf and fprintf

Instead of the final print out being: The sum of the dollar amounts is

I would like for it to display: The sum of the (%d how ever many amounts they put in) is

How do you set (the value of how many times the user input a dollar amount to be calculated) to a variable so that it can be referenced in the final printf?

Code:

void sumDoubles ()
{
	double num = 0;
	double total = 0;
	int doublesEntered = 0;
	int index;
	double amounts[100];
	
	FILE *myFile;
	myFile = fopen("assignment3.txt", "w");

		printf("\nI want to sum up dollar amounts.\n\n");
		fprintf(myFile, "You chose to sum a list of dollar amounts.\n\nThese are the dollar amounts:\n\n");
	
		
		do
	{	
		printf("\nEnter an dollar amount (enter -1 to quit): \n\n\t\t\t");
		scanf("%lf", &num);
					

			if (num != -1 )
				{    
				amounts[doublesEntered] = num;  // store each num in the array
				doublesEntered++;  // advance the index by 1 for the next num 
			
				fprintf(myFile, "$%.2f\n", num);
			
				total += num;
				printf("\n\tThe total so far is: $%.2f\n", total);
				}
		
			else
		
				break;
				
	}	while(num != -1);

	

								for (index = 0; index < num; index++) 
								{
								total += amounts[index];
								}



		fprintf(myFile, "\nThe sum of the dollar amounts is $%.2f", total);
		printf("\nThe sum of the dollar amount is $%.2f\n\n\n", total);
		printf("\tThank you for playing!\n\n\n\n");

		fclose(myFile);

	return;
}

In another words, how can I print the number of elements in the array?

Instead of

Code:

 if (num != -1)

try

Code:

 for(i = 0; i != -1; i++)

this will help you keep track of the total number of inputs

hopefully that helps. Im still a rookie so if not my bad.

Originally Posted by grumpy

The variable doublesEntered keeps track of the number of values entered. Print its value using the %d format.

Grumpy is right though, doublesEntered keeps track of the number of values entered just as i in my previous post would.

Thanks.

I tried implementing the same fix for my other function and got a negative result. Can anyone help explain why I'm getting the wrong value for the number of elements in the array? And also what I should work on to fix it?

Code:

void sumIntegers ()
{
int arr[100];
int i;
int num = 0;
int sum = 0;

FILE *myFile;
myFile = fopen("assignment3.txt", "w");
	

		printf("\nI want to sum up even integers <= 50.\n\n");


		do
	{
		printf("\n\nPlease enter a positive integer:\n\n\t\t\t");
		scanf("%d", &num);
		
		fprintf(myFile, "You chose to sum the even integers from 0 to %d.\n\n", num);
		
		
			if(num < 0)
				{
				printf("\n*** Negative numbers are invalid! ***\n\n\n");
				break;
				}
	
			
					
							for (i = num - 4; i >= 0; i--)
							{
							arr[i] = (i + 1) * 2;	// add 1 to the index, then double it, and store that # in arr
							printf ("\nIn index #%d of arr, we stored the value %d.\n", i, arr[i]);    //prints arr[i] with index reference
					
							fprintf(myFile, "%d\n\n", arr[i]);    //prints to txt file
							}



		printf("\n");
					


							for (i = num - 4; i >= 0; i--)
							{
							sum += arr[i]; // add each element to "sum"
							}


		printf("\n\nThe total of the %d even element in arr[i] = %d.\n\n\n\n", i, sum);
		fprintf(myFile, "The sum of the %d even integers is: %d", i, sum);	//prints to txt file
	
	}	while(num <= 0);


	fclose(myFile);
	
	return;
}

Code:

    for (i = num - 4; i >= 0; i--)
    {
         sum += arr[i]; // add each element to "sum"
    }
    printf("\n\nThe total of the %d even element in arr[i] = %d.\n\n\n\n", i, sum);

Are you aware that this will alwais print

Code:

The total of the -1 even element ...

because i will always be -1 after the loop.

I do not understand why your loops need to count backwards

Kurt

Originally Posted by ZuK

Code:

    for (i = num - 4; i >= 0; i--)
    {
         sum += arr[i]; // add each element to "sum"
    }
    printf("\n\nThe total of the %d even element in arr[i] = %d.\n\n\n\n", i, sum);

Are you aware that this will alwais print

Code:

The total of the -1 even element ...

because i will always be -1 after the loop.

I do not understand why your loops need to count backwards

Kurt

Yes I'm aware. I seem to like making things harder than they are and need to be. Why do I tend to figure things out right after I post a thread asking for help?