教程iPhone計算器小數點

Question

可能重複：
How do I change the number of decimal places iOS?
If using Xcode to make an iOS calculator, how would I add a decimal button?

我正在尋找關於如何使一個（簡單）iPhone的計算器，可以在iOS教程至少要做到以下幾點：加，減，乘，除，並讓用戶輸入小數點。我一直無法找到這樣的教程，所以如果有人知道，請告訴我。我其實可以找到一個可以加，減，乘，除的小數點，但不能做小數點。如果您可以告訴我如何讓用戶輸入小數點，則不需要進一步的教程。我現在使用的代碼如下。

在頭文件：

#import <UIKit/UIKit.h> 

@interface CalculatorViewController : UIViewController { 

float result; 
IBOutlet UILabel *calculatorScreen; 
int currentOperation; 
float currentNumber; 

} 


-(IBAction)buttonDigitPressed:(id)sender; 
-(IBAction)buttonOperationPressed:(id)sender; 
-(IBAction)cancelInput; 
-(IBAction)cancelOperation; 

主文件

：

#import "CalculatorViewController.h" 

@implementation CalculatorViewController 


-(IBAction)buttonDigitPressed:(id)sender { 


currentNumber = currentNumber *10 + (float)[sender tag]; 
calculatorScreen.text = [NSString stringWithFormat:@"%.1f", currentNumber]; 

}

-(IBAction)buttonOperationPressed:(id)sender { 
if (currentOperation ==0) result = currentNumber; 
else {   

    switch (currentOperation) { 
     case 1: 
      result = result + currentNumber; 
      break; 
     case 2: 
      result = result - currentNumber; 
      break; 
     case 3: 
      result = result * currentNumber; 
      break; 
     case 4: 
      result = result/currentNumber; 
      break; 
     case 5: 
      currentOperation = 0; 
      break; 

    } 
} 

currentNumber = 0; 
calculatorScreen.text = [NSString stringWithFormat:@"%.1f", result]; 
if ([sender tag] ==0) result=0; 
currentOperation = [sender tag]; 
} 



-(IBAction)cancelInput { 

currentNumber =0; 
calculatorScreen.text = @"0"; 

} 


-(IBAction)cancelOperation { 



currentNumber = 0; 
calculatorScreen.text = @"0"; 
currentOperation = 0; 

} 

Answer 1

這應該工作。簡單而直接。

更改currentNumber以存儲正在進行的計算的當前字符串值（設爲NSMutableString），爲小數點按鈕添加一個插座（buttonDecialPointPressed）。

-(IBAction) buttonDigitPressed:(id)sender 
{ 
    currentNumber = [currentNumber appendFormat:@"%d"]; 
    calculatorScreen.text = currentNumber; 
} 

- (IBAction) buttonDecialPointPressed:(id)sender 
{ 
    if(behindTheDecimal == YES) 
     return; 
    behindTheDecimal = YES; 
    currentNumber = [currentNumber appendString:@"."]; 
    calculatorScreen.text = currentNumber; 
} 

-(IBAction)buttonOperationPressed:(id)sender 
{ 
    float number = [currentNumber floatValue]; 
    switch (currentOperation) 
    { 
     case 0: 
      result = number; 
      break; 
     case 1: 
      result = result + number; 
      break; 
     case 2: 
      result = result - number; 
      break; 
     case 3: 
      result = result * number; 
      break; 
     case 4: 
      result = result/number; 
      break; 
     case 5: 
      currentOperation = 0; 
      break; 
     case 6: 
      break; 
    } 

    currentNumber = [currentNumber stringWithFormat:@"%f", result]; 
    calculatorScreen.text = currentNumber; 

    // why is this needed, how is it used? 
    currentOperation = [sender tag]; 
} 


-(IBAction)cancelInput 
{ 
    behindTheDecimal = NO; 
    currentNumber = @"0"; 
    calculatorScreen.text = currentNumber; 
} 

-(IBAction)cancelOperation 
{ 
    behindTheDecimal = NO; 
    currentNumber = @"0"; 
    calculatorScreen.text = currentNumber; 
    currentOperation = 0; 
}