Question

How would I make the following calculator Class work?:

//Calculator.h

#import <Cocoa/Cocoa.h>

@interface Calculator : NSObject {
    float initialNumber, operandNumber;
    typedef enum{
    additionOperation,
    subtractionOperation,
    multiplicationOperation,
    divisionOperation
    }operationType;
}

@property(readwrite) float initialNumber, operandNumber;
@property(readwrite) enum operationType; //Line 16

- (float) doOperation;

@end

In XCode 3.1.3 I get an “error: syntax error before ‘typedef'” and a “warning: declaration does not declare anything” at line 16 of Calculator.h

//Calculator.m

#import "Calculator.h"

@implementation Calculator
@synthesize initialNumber, operandNumber, operationType;

-(float) doOperation{
    switch (self.operationType){  //Line 9
        case 0:
            return self.initialNumber + self.operandNumber;
            break;
        case 1:
            return self.initialNumber - self.operandNumber;
            break;
        case 2:
            return self.initialNumber * self.operandNumber;
            break;
        case 3:
            return self.initialNumber / self.operandNumber;
            break;
        default:
            return 0;
            break;
    }
}

@end

In the implementation, XCode gives me “no declaration of property ‘operationType’ found in the interface” and “request for member ‘operationType’ is something not a structure or union.” Am I declaring my enums correctly?

Additionally, in switch statements, can I use “case additionOperation” or do I have to use “case 0”?

Answer 1

Move your enum declaration out of the class declaration. You can put it right above. And You may want to rename the typedef to ‘OperationType’. Then where you have the declaration now, declare a variable of that type: ‘OperationType operationType;’