Question

Exercise:

“Complex numbers are numbers that contain two components: a real part and an
imaginary part. If a is the real component and b is the imaginary component, this
notation is used to represent the number:
a + b i
Write an Objective-C program that defines a new class called Complex. Following
the paradigm established for the Fraction class, define the following methods for
your new class:

-(void) setReal: (double) a;
-(void) setImaginary: (double) b;
-(void) print; // display as a + bi
-(double) real;
-(double) imaginary;

Write a test program to test your new class and methods.”

Here is my solution that doesn’t work:

    #import <Foundation/Foundation.h>

@iterface Complex:NSObject
{
    double a, b;
}

-(void)setReal: (double) a;
-(void)setImaginary: (double) b;
-(void) print;
-(double) real;
-(double) imaginary;

@end

@implementation Complex
-(void)setReal
{
    scanf(@"Set real value %f",&a);
}
-(void)setImaginary
{
    scanf(@"Set imaginary value %f", &b);
}
-(void) print
{
    Nslog(@"Your number is %f",a+bi);
}
-(double)real
{
    Nslog(@"Real number is %f",a);
}
-(double)imaginary
{
    NSlog(@"Imaginary number is %f",b)
}

@end



int main (int argc, char *argv[])
{
    NSAutoreleasePool *pool=[[NSAutoreleasePool alloc] init];
    Complex*num=[[complex alloc] init];
    [num setReal:3];
    [num setImaginary:4];
    Nslog(@"The complex number is %i",[num print]);
    [num release];
    [pool drain];
    return 0;
}

Please, what is wrong?

Answer 1

There are a few obvious flaws that I can see. First, (and this may be a copy/paste error), you misspelled interface as iterface.

Second, your print method does not write to the NSLog correctly. You’re trying to force an expression a+bi as the result to the format specifier %f. Instead, you’ll want to have two arguments, with both a and b being passed separately to the NSLog call. Thus you’d have:

    NSLog(@"Your number is %f + %fi", a, b);

Lastly, your methods real and imaginary are supposed to be ‘getters’ for your instance variables, not functions that print to NSLog. Thus, you’ll instead just want the function bodies to be return a; and return b; respectively. For the former (in full):

    -(double)real
    {
        return a;
    }