Prog 3.2 errors :(

[a13x612]

Hi all,

First time on boards, just started learning objective-c.  I'm still pretty new to programming and have limited experience so please bear with me.

I typed prog 3.2 into xcode but i keep getting errors.  Below is the code and attached is the screenshot of the errors:

#import <Foundation/Foundation.h>

//---- @interface section
@interface Fraction: NSObject

-(void) print;
-(void) setNumerator: (int) n;
-(void) setDenominator: (int) d;

@end

//-----implementation section
@implementation Fraction
{
    int numerator;
    int denominator;
}

-(void) print
{
    nslog(@"%i/%i",numerator,denominator);
}

-(void) setnumerator: (int) n
{
    numerator = n;
}

-(void) setdenominator: (int) d
{
    denominator = d;
}

@end;

//----program section

int main (int argc, char * argv[])
{
   
    @autoreleasepool {
        Fraction *myFraction;
       
        //create an instance of a fraction.
       
        myFraction=[Fraction alloc];
        myFraction=[myFraction init];
       
        //set fraction to 1/3
       
        [myFraction setNumerator:1];
        [myFraction setDenominator:3];
       
        //Display fraction using print method
       
        NSLog(@"The value of myFraction is:");
        [myFraction print];
       
    }
    return 0;
}

Can anyone help me out on this?

Thanks!

[skochan]

Pay attention to case in your letters; case is significant.

setNumerator
setDenominator
NSLog

I don't understand the "Inconsistent number of instance variables error."  I copied your posted code into Xcode and I'm not seeing that error.  I'll try to look further.

Cheers,

Steve

[a13x612]

I fixed the syntax on everything and i retyped the lines with the strange errors on them, ran it, and it worked! don't know what i did exactly to make them go away. thank you for your help, i will definitely be back!

[skochan]

Yoiu're welcome!  We're always here to help.! 

Cheers,

Steve

[a13x612]

In an attempt to understand what happened to make it work I retyped the code and the same errors are popping up again.


#import <Foundation/Foundation.h>

//--- @interface section ---

@interface Fraction: NSObject

-(void) print;
-(void) setNumerator: (int) n;
-(void) setDenominator: (int) d;

@end

//--- @implementation section ---

@implementation Fraction

{
    int numerator;
    int denominator;
}
-(void) print
{
    NSLog(@"%i/%i", numerator, denominator);
}

-(void) setNumerator: (int) n
{
    numerator = n;
}

-(void) setDenominator: (int) d
{
    denominator = d;
}

@end

//--- program section ---

int main (int argc, char * argv[])
{
    @autoreleasepool {
        Fraction *myFraction;
       
        //Create an instance of a Fraction
       
        myFraction = [Fraction alloc];
        myFraction = [myFraction init];
       
        //Set fraction to 1/3
       
        [myFraction setNumerator: 1];
        [myFraction setDenominator: 3];
       
        //Display fraction using print method
       
        NSLog (@"The value of myFraction is:");
        [myFraction print];
    }
   
    return 0;
}

See attached image for errors.  This is getting beyond frustrating and i'm thinking it is the actual software that is screwing up and not the code itself.

[Waiting]

I copy and pasted this into a fresh file and it works fine.

Maybe try a fresh project.

In an attempt to understand what happened to make it work I retyped the code and the same errors are popping up again.


#import <Foundation/Foundation.h>

//--- @interface section ---

@interface Fraction: NSObject

-(void) print;
-(void) setNumerator: (int) n;
-(void) setDenominator: (int) d;

@end

//--- @implementation section ---

@implementation Fraction

{
    int numerator;
    int denominator;
}
-(void) print
{
    NSLog(@"%i/%i", numerator, denominator);
}

-(void) setNumerator: (int) n
{
    numerator = n;
}

-(void) setDenominator: (int) d
{
    denominator = d;
}

@end

//--- program section ---

int main (int argc, char * argv[])
{
    @autoreleasepool {
        Fraction *myFraction;
       
        //Create an instance of a Fraction
       
        myFraction = [Fraction alloc];
        myFraction = [myFraction init];
       
        //Set fraction to 1/3
       
        [myFraction setNumerator: 1];
        [myFraction setDenominator: 3];
       
        //Display fraction using print method
       
        NSLog (@"The value of myFraction is:");
        [myFraction print];
    }
   
    return 0;
}

See attached image for errors.  This is getting beyond frustrating and i'm thinking it is the actual software that is screwing up and not the code itself.

[a13x612]

Tried that.  is it because i'm running xcode 4 on snow leopard?

[skochan]

It's bizarre.

Steve

[a13x612]

I figured it out.

In the implementation section:

//--- @implementation section ---

@implementation Fraction

{
    int numerator;
    int denominator;
}
-(void) print
{
    NSLog(@"%i/%i", numerator, denominator);
}

-(void) setNumerator: (int) n
{
    numerator = n;
}

-(void) setDenominator: (int) d
{
    denominator = d;
}

@end

The issue was the curly braces before and after "int numerator" and "int denominator".  Once I removed those, the program worked.

-.-

[Deusexmachina]

Hi,

It might be a version thing. I've tried to follow some XCode 4 examples and got several errors because I had a newer version (xcode 4.2xxx). I downloaded my version of Xcode last November but I've seen diffences with code written back in July.

What version of Xcode do you see in the splash screen when you start the program?

Best,

DEM

[a13x612]

Its version 4.2.  But then my question becomes how can I keep up if the code is always changing? And where can I go to look at updated versions of these examples (if possible)?

[Bunchadna]

I got the same errors

use of undeclared identifier 'n' 

If I expand the message, it says

local declaration of 'numerator' hides instance variable

Removing the braces didn't help.

I'll post a screen shot later - when I figure out how to do it.  I'm brand new to mac and am pedaling quickly up the learning curve ... ;-)

[Bunchadna]

I'm having trouble and really need help.  I was getting the same error messages, so I tried changing the name of the variable to "mynumerator" and "mydenominator" because the error message seemed to indicate that the names "numerator" and "denominator" were reserved in some sense.  Anyway, here's my code.  Any help is greatly appreciated.  Note that I still get errors "Local declaration of "mynumerator" hides instance variable."


#import <Foundation/Foundation.h>

// ----------- @interface section ---------

@interface Fraction: NSObject

-(void)     print;
-(void)     setNumerator:  (int) n;
-(void)     setDenominator:  (int) d;

@end

//------@Implementation section ----

@implementation Fraction

{    
    int mynumerator;
    int mydenominator;
}

-(void)  print
{
    NSLog (@"\n%i/%i", mynumerator, mydenominator);
}

-(void) setNumerator:  (int) mynumerator
{
    mynumerator = n;
}

-(void) setDenominator:  (int) mydenominator
{
    mydenominator = d;
}

@end

//------Program section ------

int main (int argc, char * argv[])
{
    @autoreleasepool {
        Fraction  *myFraction;
        
        //  Create an instance of a fraction
        
        myFraction = [Fraction alloc];
        
        myFraction = [myFraction init];
        
        //  Set fraction to 1/3
        
        [myFraction setNumerator: 1];
        [myFraction setDenominator: 3];
        
        //  Display the fraction using print method
        
        NSLog (@"\nThe value of myFraction is:");
        [myFraction print];
        
    }
    
    return 0;
}

[Waiting]

Code: (Objective-C)

@interface Fraction: NSObject

-(void)     setNumerator:  (int) n;
-(void)     setDenominator:  (int) d;

@end

-(void) setNumerator:  (int) mynumerator
{
    mynumerator = n;
}

-(void) setDenominator:  (int) mydenominator
{
    mydenominator = d;
}

@end

In the interface section you say you will send setNumerator an integer called n, then in the implementation section you say you will send it the int mynumerator.

The compiler is confused by the use of mynumerator when it is already in the fraction implementation.

Secondly you try to set mynumerator to n, however n does not exist as you have changed the implementation so that it is no longer there.

Look at the code below and it should help you realise where you went wrong.

Code: (Objective-C)

//--- @interface section ---

@interface Fraction: NSObject

-(void) print;
-(void) setNumerator: (int) n;
-(void) setDenominator: (int) d;

@end

//--- @implementation section ---

@implementation Fraction

{
    int numerator;
    int denominator;
}
-(void) print
{
    NSLog(@"%i/%i", numerator, denominator);
}

-(void) setNumerator: (int) n
{
    numerator = n;
}

-(void) setDenominator: (int) d
{
    denominator = d;
}

[Bunchadna]

Thank you for responding.  I got it to work the way it's presented in the text.