Excersise 6.2 Solution

[Random Logic]

I am looking for feedback on my solution to the invalid operator please.

#import <Foundation/Foundation.h>

@interface Calculator : NSObject   

// accumulator methods

-(void) setAccumulator: (double) value;
-(void) clear;
-(double) accumulator;

// arithmetic methods

-(void) add: (double) value;
-(void) subtract: (double) value;
-(void) multiply: (double) value;
-(void) divide: (double) value;

@end

@implementation Calculator

{
    double accumulator;
}

-(void) setAccumulator: (double) value;
{
    accumulator = value;
}

-(void) clear
{
    accumulator = 0;
}

-(double) accumulator
{
    return accumulator;
}

-(void) add: (double) value
{
    accumulator += value;
}

-(void) subtract: (double) value
{
    accumulator -= value;
}

-(void) multiply: (double) value
{
    accumulator *= value;
}

-(void) divide: (double) value
{
    if (value == 0){
        printf("Error - Divide by Zero ");
        accumulator = 0;
    }
    else
        accumulator /= value;
}

@end

int main (int argc, char * argv[])
{
    @autoreleasepool {
        double value1, value2;
        char operator;
        bool test = YES;
        Calculator *deskCalc = [[Calculator alloc]init];
        printf("Type in your expression: ");
        scanf("%lf  %c  %lf", &value1, &operator, &value2);
       
        [deskCalc setAccumulator: value1];
       
        switch (operator){
            case '+':
                [deskCalc add: value2];
                test = YES;
                break;
            case '-':
                [deskCalc subtract: value2];
                test = YES;
                break;
            case '*':
                [deskCalc multiply: value2];
                test = YES;
                break;
            case '/':
                [deskCalc divide: value2]; 
                test = YES;
                break;
            default:
                printf(" Unknown operator.");
                test = NO;
                break;
        }
        if (test == YES)
            printf("%.2f", [deskCalc accumulator]);
        [deskCalc release];
        if (test == NO)
        {
            printf("");
           
        }
       
       
       
    }
   
    return 0;
}