Question

错误

已声明实例变量

类型名称需要说明符或限定符

预期';'在声明清单的末尾

我无法弄清楚为什么会这样。请帮忙！

这是我的代码：

ViewController.m

#import "evalViewController.h"

@interface evalViewController () {
    digits[10] = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9'}; //Errors: Instance variable is already declared, Type name requires a specifier or a qualifier, Expected ';' at end of declaration list 

    }

@end

@implementation evalViewController 

@synthesize terminal;
@synthesize expression; 

//Add iEval prefix to output
-(void)writeToTerminal:(NSString *)string {
    self.terminal.text = [NSString stringWithFormat:@"ConsoleCalc> %@", string];
}


- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.

    //Define operation characters
    self.add = '+';
    self.sub = '-';
    self.mult = '*';
    self.div = '/';

    //Define digits to compare to digits in editableExpression 
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}


- (IBAction)evaluate:(UITextField *)sender {
    //Set user input to NSString editableExpression
    NSString *editableExpression = self.expression.text;

    //Loop through new NSString
    for (int i=0; i < editableExpression.length; i++ ){
        char charAtPosition = [editableExpression characterAtIndex:i];
        //Check if there is a + sign anywhere in the expression and write "Addition!" if there is
        if (charAtPosition == self.add){
            if ([self checkForDigits]){
                 [self writeToTerminal:@"There are digits in this string!"];
            }
            else {
                 [self writeToTerminal:@"There are no digits in this string!"];
             }

         }
         //Check if there is a - sign anywhere in the expression and write "Subtraction!" if there is
        else if (charAtPosition == self.sub) {
             [self writeToTerminal:@"Subtraction!"];

         }

        //Check if there is a * sign anywhere in the expression and write "Multiplication!" if there is
        else if (charAtPosition == self.mult) {
             [self writeToTerminal:@"Multiplication!"];
        }

        //Check if there is a / sign anywhere in the expression and write "Division!" if there is
        else if (charAtPosition == self.div) {
            [self writeToTerminal: @"Division!"];
        }

    }

 }

//clear the terminal

- (IBAction)clearTerminal:(id)sender {
     [self writeToTerminal:@""];
 }

- (BOOL)checkForDigits {
    NSString *editableExpression = self.expression.text;
    for (int i = 0; i < editableExpression.length; i++){
        char charAtPosition = [editableExpression characterAtIndex:i];
        for (int c = 0; c < 10; c++ ){
            if (charAtPosition == digits[c]){
                return true;
            }
            else {
                return false;
            }
        }



    }
}

@end

ViewController.h

#import <UIKit/UIKit.h>

@interface evalViewController : UIViewController {
     char digits[10];

 }

//Large text view
@property (strong, nonatomic) IBOutlet UITextView *terminal;

//User input
@property (strong, nonatomic) IBOutlet UITextField *expression;

//Evaluate expression
- (IBAction)evaluate:(UITextField *)sender;

- (IBAction)clearTerminal:(id)sender;

//Operation characters
@property char add;
@property char sub;
@property char mult;
@property char div;

//Change to information view
 - (void)writeToTerminal: (NSString *) string;
 - (BOOL)checkForDigits;




@end

Answer 1

您正在声明数组错误。完全从标头中删除它，并仅在实现文件（.m文件）中声明digits char数组。然后错误就会消失。此外，您正在错误地分配值。您正在创建一个包含10个元素的char数组，然后您将*另一个char数组分配给第10个索引处的元素，该数组始终不存在. There are multiple errors there. It should be digits = {...} not个数字[10] = {...}`。

如果我是你，我将首先开始学习普通C并在进入Objective-C之前获得基础知识，因为它只会使复杂化更复杂。我看到你想创建iOS应用程序，但为了简化这个过程，你首先需要了解C井的基础知识。

Answer 2

我的措辞可能不对，但您正在初始化界面中的数字。这样做。

您可以在.m文件中执行此操作（并且不需要@interface evalViewController（）@end只显示放置它的位置）

char digits[10] = { ... };

@interface evalViewController ()

@end

在尝试定义字符数组时，我一直遇到三个错误

2 个答案: