Question

我按照教程制作了一个iOS计算器，我现在想要添加一个小数位的按钮。这是我的代码

头文件：

#import <UIKit/UIKit.h>

@interface CalcViewController : UIViewController {

float result;
float selectedNumber;

int selectedOperation;

IBOutlet UILabel *calcScreen;
}

-(IBAction)numberPressed:(id)sender;
-(IBAction)operationPressed:(id)sender;
-(IBAction)clearNumber:(id)sender;
-(IBAction)clearOperation:(id)sender;

@end

这是我的实施文件

#import "CalcViewController.h"

@implementation CalcViewController

-(IBAction)numberPressed:(id)sender {
selectedNumber = selectedNumber * 10 + (float) [sender tag];
calcScreen.text = [NSString stringWithFormat:@"%2g", selectedNumber];
}

-(IBAction)operationPressed:(id)sender {
if (selectedOperation == 0) {
    result = selectedNumber;

} else {
    switch (selectedOperation) {
        case 1:
            result = result + selectedNumber;
            break;
        case 2:
            result = result - selectedNumber;
            break;
        case 3:
            result = result * selectedNumber;
            break;
        case 4:
            result = result / selectedNumber;
            break;
        case 5:
            selectedOperation = 0;
            break;



    }
}
selectedNumber = 0; 
calcScreen.text = [NSString stringWithFormat:@"%2g", result];
if ([sender tag] == 0) result = 0;
selectedOperation = [sender tag];

} 


-(IBAction)clearNumber:(id)sender {
selectedNumber = 0;
calcScreen.text = @"0";
}

-(IBAction)clearOperation:(id)sender {
selectedNumber = 0;
calcScreen.text = @"0";
selectedOperation = 0;
}

我在另一个帖子上看到有人建议使用该方法：

- (IBAction)Decimal:(id)sender 
{
 NSString *currentText = calcScreen.text;
 if ([currentText rangeOfString:@"." options:NSBackwardsSearch].length == 0) {
    calcScreen.text = [calcScreen.text stringByAppendingString:@"."];  
}

然而，这似乎对我没有用。它确实会让我输入一个小数点，但是当输入第二个数字时，小数点将会丢失。任何人都可以建议我可以实现的方法来实现我的目标吗？

提前干杯！

Answer 1

我的想法是：将数字作为文本保留在屏幕上，将其他数字和/或小数点添加为文本。在执行操作时，只将它转换为浮点数（我会自己使用double，btw）。建议的方法应该可以正常工作。

类似的东西：

-(IBAction)numberPressed:(id)sender {
    calcScreen.text = [calcScreen.text stringByAppendingString:[sender tag]];
}

-(IBAction)operationPressed:(id)sender {
    selectedNumber = [calcScreen.text floatValue];
    ...
}

Answer 2

一个快速提示，而不是使用 int selectedOperation;...以及稍后的代码

switch (selectedOperation) {
    case 1:
        result = result + selectedNumber;
        break;
    case 2:
        result = result - selectedNumber;
    ...

尝试使用typedef enum

    typedef enum {
    OperationTypeAdd = 0,
    OperationTypeSub,
    ...
    } OperationType

并在switch块

中

    switch (operationType) {
    case OperationTypeAdd:
        result = result + selectedNumber;
        break;
    case operationTypeSub:
        result = result - selectedNumber;
        break;

将小数点按钮添加到iOS计算器

2 个答案: