Need help with conversions in C

green_dragon37 · 06-06-2003, 11:41 PM

Hi all!

I've been messing around trying to learn C. I bought a book from O'Rielly called Practical C Programming. After a few chapters, I ran into an excercise that suggests writing a program to convert Centigrade to Farenheit, so I said, "How about a program that converts both ways??" Some of it works fine, but when I try to do conversions, the F-to-C conversion always produces -32.000000, and the C-to-F always produces whatever I input + 32. Could anyone help me figure this out??

Here is what i have so far:

Code:

#include <stdio.h>

char type; /* Type of conversion */
float far; /* Temp in Degrees Farenheit */
float cel; /* Temp in Degreen Celcius */
float result; /* Result of calculation */
char line[100]; /* Input Line */

int main()
{
	while (1){
	printf("Enter Type of Conversion;\n ? for help, q to quit:");

	fgets(line, sizeof(line), stdin);
	sscanf(line, "%c", &type);
	if((type == 'q') || (type == 'Q'))
		break;
	switch(type) {
		case 'f':
			printf("Enter temperature in degrees Farenheit: ");
			fgets(line, sizeof(line), stdin);
			sscanf(line, "%f", &far);
			cel = (5 / 9) * (far - 32);
			printf("%f Degrees Celcius\n", cel);
			break;
		case 'c':
			printf("Enter temperature in degrees Celcius: ");
			fgets(line, sizeof(line), stdin);
			sscanf(line, "%f", &cel);
			far = ((9 / 5) * cel) + 32;
			printf("%f Degrees Farenheit\n", far);
			break;
		case '?':
			printf("Type f for farenheit-celcius conversion;\nType c for celcius-farenheit conversion;\nQ to quit;\n? for help\n");
		default:
			printf("Unrecognised Command:  Type ? for help.\n");
		}
	}
}

Any help will be appreciated

Ian

green_dragon37 · 06-07-2003, 01:03 AM

Nevermind, I found my mistake. I had set up the variables as floating point, but on the lines performing the calculations, I used integers. So where I used

Code:

cel = (5 / 9) * (far + 32);

I should have used

Code:

cel = (5.0 / 9.0) * (far +32.0);

What a

mistake, huh.

Ian