Fahrenheit-Celsius Conversion Program in C

Troublesome · 25-09-2007 11:58am #1

I am trying to write a program in C for class that converts Fahrenheit to Celsius and created this:

[PHP]#include <stdio.h>
#define GIVEN_ONE 9/5
#define GIVEN_TWO 32

double main()

{
double fahr, cels;

/* Entering temperature in Fahrenheit */
printf("Enter the temperature in Fahrenheit: ");
scanf("%lf", &fahr);

/* Formula for converting Fahrenheit to Celsius */
fahr = cels * GIVEN_ONE + GIVEN_TWO;

/* Give temperature in Celsius */
printf("The temperature is %f in Celsius. \n", cels);

return(0);
} [/PHP]

I was hoping it would work but the output in Celsius just comes out to 0.00000. Anyone with knowledge in C that can help?

Tom Dunne · 25-09-2007 12:13pm

Troublesome wrote:

I am trying to write a program in C for class that converts Fahrenheit to Celsius and created this:

[php]#include <stdio.h>
#define GIVEN_ONE 9/5
#define GIVEN_TWO 32

double main()

{
double fahr, cels;

/* Entering temperature in Fahrenheit */
printf("Enter the temperature in Fahrenheit: ");
scanf("%lf", &fahr);

/* Formula for converting Fahrenheit to Celsius */
fahr = cels * GIVEN_ONE + GIVEN_TWO;

/* Give temperature in Celsius */
printf("The temperature is %f in Celsius. \n", cels);

return(0);
} [/php]
I was hoping it would work but the output in Celsius just comes out to 0.00000. Anyone with knowledge in C that can help?

You are reading in fahr, then you are setting fahr to (cels * given_one + given_two). As cels is undefined, it defaults to zero. Therefore zero * anything=0.

Smoggy · 25-09-2007 1:25pm

*sniff* smells like homework

Doctor DooM · 25-09-2007 1:28pm

fahr = cels * GIVEN_ONE + GIVEN_TWO;

is the prob, think you need to swap them, cels is currently = 0.

Edit Oops, sorry, didnt see the answer there.

The OP actually says its for class!

irlrobins · 25-09-2007 1:28pm

you don't say...;)

looks like UCD Eng stuff to me.... But as Tom says you have fahr = cels instead of cels =fahr.

um7y1h83ge06nx · 25-09-2007 1:56pm

Looks like the lads have solved your problem but just have to reply to say that this thread has got me all nostalgic about being in college!

Hope you enjoy college and programming, they're hard to beat!

Tom Dunne · 25-09-2007 2:02pm

SDooM wrote:

fahr = cels * GIVEN_ONE + GIVEN_TWO;

is the prob, think you need to swap them, cels is currently = 0.

I wasn't actually going to give him the full answer.

monkey tennis · 25-09-2007 3:04pm

Think I remember this one from K&R...

Now that your problem has been solved, why are you telling main() to return a double?

Creamy Goodness · 25-09-2007 5:53pm

Smoggy wrote:

*sniff* smells like homework

doesn't matter if it is or not

, at least s/he made an attempt at it, so when other posters point out the mistakes s/he will learn more from it than just coming on here and asking:

"i need a temperature convertor, write me one now!!!1"

not everyone is a perfect programmer, and it often takes another set of eyes to figure out mistakes.

and to be totally pedantic about it, s/he says it's for class

mach1982 · 27-09-2007 9:39am

One tip all C programs should start with int main()

monkey tennis · 27-09-2007 4:31pm

mach1982 wrote:

One tip all C programs should start with int main()

IIRC, the explicit 'int' isn't necessary, as all functions are assumed to return an int by default in C.

Fahrenheit-Celsius Conversion Program in C

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