Thread: Hello, could I get a pointer for this?

Hi all

I'm extremely new to coding. I have been working on this piece for a school assignment for a couple days now and I am stuck. Basically it is to come up with tax amounts and total sales for a fictional company. It compiles fine, but it doesn't seem to want to return valid input. No matter what amount I enter in as input, I always get "invalid input" returned. I can't figure out why because it looks right to me. Can someone point me in the right direction please?

Code:

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

int main()
{

// Declare variables

float sales = 0.0;
float trateDelmar = .0725;
float trateEncinitas = .0750;
float trateLajolla = .0775;
float staxDelmar = 0.0;
float totamtDelmar = 0.0;
float staxEncinitas = 0.0;
float totamtEncinitas = 0.0;
float staxLajolla = 0.0;
float totamtLajolla = 0.0;
char input[10];

	// Program header
	printf("\nTax calculation program for Kudler stores\n");
	printf("\nEnter Purchase Amount: ");
	
	// Read the input and assign it to sales
	scanf("%s", input);
	sales = atof(input);
	
	if(sales <= 0.0);
	{
		printf("Invalid input \n");
                return 1;
        }
        // Calculating the sales tax and total amount
        staxDelmar = trateDelmar * sales;
        totamtDelmar = staxDelmar + sales;
        staxEncinitas = trateEncinitas * sales;
        totamtEncinitas = staxEncinitas + sales;
        staxLajolla = trateLajolla * sales;
        totamtLajolla - staxLajolla + sales;
        
        // Displaying the tax rate, sales tax and total amount	
	printf("\n        \tTax\tSales\tTotal\n");
	printf("District\tRate\tTax\tSale Amount\n");
	printf("------------------------------\n");
	printf("Del Mar       \t%4.2f\t%4.2f\t%4.2f\n", trateDelmar, staxDelmar, totamtDelmar);
	printf("Encinitas     \t%4.2f\t%4.2f\t%4.2f\n", trateEncinitas, staxEncinitas, totamtEncinitas);
	printf("LaJolla       \t%4.2f\t%4.2f\t%4.2f\n", trateLajolla, staxLajolla, totamtLajolla);
	
	return 0;	
}

// End of program

I just don't understand why this isn't working. If someone can see why, an explanation would be great. I am having a hard time understanding why this doesn't work correctly.

Thanks!

Code:

if(sales <= 0.0);

When you declare sales, you set it to 0.0. Then, you do nothing else with it until you compare sales to being <= 0.0.

And it is.

Todd

Originally Posted by Todd Burch

When you declare sales, you set it to 0.0. Then, you do nothing else with it until you compare sales to being <= 0.0.

And it is.

The OP does assign to it with

Code:

      sales = atof(input);

although I don't understand why he doesn't just read it in directly as a float with

Code:

      scanf("%f", &sales);

Originally Posted by robatino

The OP does assign to it with

You're right. Missed that. I need to either sit closer to the monitor, put on my glasses, or bump the font size a bit!! Good catch.

We are supposed to have it validate. So I needed a way to invalidate someone putting in a non numeric input. Was this not the right way to do this?

Right here:

Code:

sales = atof(input);

add this in:
printf("%f", sales);

and you'll see what's going on perhaps, for yourself.

I'm no expert on validating input, but I believe the standard approach would be to use
fgets(buffer, size of buffer, stdin);

and then to use sscanf, etc., on buffer to "get it clean and separated.

That is beyond the scope of this assignment, fortunately. A char should return invalid input and a number should proceed with the process. I can see it is assigning sales my input but it is running the "if" statement regardless of what I input.

I appreciate the responses and will dig at this more considering what I have been told.

Thank you all

You DID remove the semi-colon at the end of this if statement, RIGHT??

Code:

if(sales <= 0.0);

THAT definitely should not be there, and will cause a problem like you're having.

Oh man I been staring at this for too long, I didn't catch that. Thanks for the assist, that did it. This stuff can drive you nuts

Thanks again!

Originally Posted by matsp

Really? - most compilers (if not all) that I've worked with don't detect this even at the highest level of warnings.

You've presumably not worked with gcc then? It will show this with -W or -Wextra.