my calculator has problems

[umen]

Hi people,

I'm trying to write a basic calculator using GNUstep+ObjC and I get stucked. I really don't know where is the problem in my code. May you help me?

I'm sending here what I have implemented until now:

@interface UCalc : NSObject

{

  char operation; //just a char to validate the operation

  id number1, number2; //number1 = the current button pressed, number2 = the old number

  id result; //the calculator display

}

- (void) Add: (id)sender;

@end

@implementation UCalc

- (void) Add: (id)sender

{

  operation = '+';

  number2 = number1; //when you press the add button the current number becomes the old number

  number1 = @"0";

}

- (void) Button0: (id)sender

{

  number1 = @"0";

  [result setStringValue: number1];

}

- (void) Button1: (id)sender

{

  //if there is no number yet

  if (number1 == nil || [number1 isEqual: @"0"]){

    [result setStringValue: @""];

    number1 = @"1";

  }

  //else append the current number in itself, so we can get number > 9

  else{

    number1 = [number1 stringByAppendingFormat: @"1"];

  }

  [result setStringValue: number1];

}

- (void) Button2: (id)sender

{

  if (number1 == nil || [number1 isEqual: @"0"]){

    [result setStringValue: @""];

    number1 = @"2";

  }

  else{

    number1 = [number1 stringByAppendingFormat: @"2"];

  }

  [result setStringValue: number1];

}

All the others number buttons are implemented in the same way...

The problem is in Equal button:

- (void) Equal: (id)sender{

  switch(operation){

    case '+':

    //trying  to do this: number1 = number2 + number1 and then print in the display result

    [number1 setDoubleValue: [number2 doubleValue] + [number1 doubleValue]];

      [result setStringValue: number1];

      break;

   }

}

I already have created the window in Gorm, so everything is implemented there. The problem in this code is in the number1 = number2 + number1 in Equal method, I don't know why it's not assigning to number1 the operation correctly and then result working correctly. Any idea about what I'm doing wrong? Everything?

Sorry my english. Thanks.

UCalc.h
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UCalc.m
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