Question

I’m working on the book “programming in objective c 2.0” and im not understanding why this program is not working. basically i need to build a program to convert a fahrenheit value to a celcius one.

I figured to just solve it very simply without objects and just use a straight procedural methodology, any way the problem I’m having is that the values of the variables I define to represent the fahrenheit or celcius values are coming up kind of random.

Here’s my code:

#import <Foundation/Foundation.h>

int main (int argc, const char * argv[]) {
    NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
    float  fahrenheit;
    float  celciusConverted;
    fahrenheit = 27.0;
    celciusConverted = ( fahrenheit - 32 ) / 1.8 ;
    NSLog(@"%f degrees fahrenheit is equal to %f degrees celcius") , fahrenheit, celciusConverted;
    [pool drain];
    return 0;
}

Answer 1

The closing parenthesis in your NSLog statement is misplaced. It should be just before ;

What you have is

NSLog(@"... %f %f ..."), arg1, arg2;

The compiler doesn’t seem smart enough to see that none of the %f have a corresponding argument, a common pitfall with variadic functions like NSLog(). After the closing parenthesis, the comma operator kicks in and the expressions arg1 and arg2 do nothing.