Please note, this blog entry is from a previous course. You might want to check out the current one.
Add a āCā button that clears everything (for example, the display in your View, the operand stack in your Model, any state you maintain in your Controller, etc.). Make sure 3 7 C 5 results in 5 showing in the display. You will have to add API to your Model to support this feature.
Create a new label above the number display in the storyboard, change the alignment to “right”, remove its text and create a new outlet called “history”. Add a new button called “C” left to the number display and create an action “clearPressed”. Don’t forget to reduce the size of the number display accordingly.
Add a new API to CalculatorBrain.h:
- (void)clearStack;
and its implementation to CalculatorBrain.m:
- (void) clearStack { [self.operandStack removeAllObjects]; }
Finally enter the code for clearPressed in CalculatorViewController.m:
- (IBAction)clearPressed { self.display.text = @"0"; self.history.text = @""; self.userIsInTheMiddleOfEnteringANumber = NO; self.userIsInTheMiddleOfEnteringAFloat = NO; [self.brain clearStack]; }
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