Ben's solution

[webwrx]

My solution -

Code: (Objective-C)

#import <Foundation/Foundation.h>

@interface Calculator: NSObject
{
	double accumulator;
}

// 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

-(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
{
	accumulator /= value;
}

@end


int main (int argc, const char * argv[]) {
    NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
	
	double value;
	char operator;
	Calculator *deskCalc = [[Calculator alloc] init];
	
	NSLog(@"Enter Number then Operator (+ - * / S E):");
		
	do {
		
	scanf("%lf %c", &value, &operator);
	
	if (operator == 'S' || operator == 's')
		[deskCalc setAccumulator: value];
	else if (operator == '+')
		[deskCalc add: value];
	else if (operator == '-')
		[deskCalc subtract: value];
	else if (operator == '*')
		[deskCalc multiply: value];
	else if (operator == '/')
		if (value == 0)
			NSLog (@"Division by zero! Try Again.");
		else
			[deskCalc divide: value];
	else if (operator == 'E' || operator == 'e')
		NSLog (@"End of Calculations.");
	else
		NSLog (@"Unknown Operator! Try Again.");
		
	NSLog(@"= %.6f", [deskCalc accumulator]);
	
	} while (operator != 'E' || operator != 'e');
	
	
	[deskCalc release];
		
    [pool drain];
    return 0;
}

Sample output -

Code: (Objective-C)

2009-09-10 11:41:56.721 exer6-4[47807:10b] Enter Number then Operator (+ - * / S E):
4 S
2009-09-10 11:42:01.535 exer6-4[47807:10b] = 4.000000
23.4 *
2009-09-10 11:42:07.207 exer6-4[47807:10b] = 93.600000
-3 -
2009-09-10 11:42:17.616 exer6-4[47807:10b] = 96.600000
3 -
2009-09-10 11:42:25.688 exer6-4[47807:10b] = 93.600000
33 ^
2009-09-10 11:42:36.058 exer6-4[47807:10b] Unknown Operator! Try Again.
2009-09-10 11:42:36.059 exer6-4[47807:10b] = 93.600000
8 s
2009-09-10 11:42:47.352 exer6-4[47807:10b] = 8.000000
-12 +
2009-09-10 11:42:57.978 exer6-4[47807:10b] = -4.000000
0 e
2009-09-10 11:43:05.785 exer6-4[47807:10b] End of Calculations.
2009-09-10 11:43:05.785 exer6-4[47807:10b] = -4.000000

[skochan]

Looks good Ben!  As an extra exercise you might want to change the if statement to a switch.

Cheers,

Steve