Question

#import "Calculator.h"

@implementation Calculator

- (long) calcNumbers:(NSString *)myOperator andNumberOne:(NSString *)numberOne andNumberTwo:(NSString *)numberTwo {

    long result;

    if ([myOperator isEqualToString:@"+"]){
        result = [numberOne integerValue] + [numberTwo integerValue];
    } else if ([myOperator isEqualToString:@"-"]) {
        result = [numberOne integerValue] - [numberTwo integerValue];
    } else if ([myOperator isEqualToString:@"*"]){
        result = [numberOne integerValue] * [numberTwo integerValue];
    } else if ([myOperator isEqualToString:@"/"]) {
        result = [numberOne integerValue] / [numberTwo integerValue];
    } else {
        result = [numberOne integerValue] % [numberTwo integerValue];
    }

    return result;

}


- (long) postFix:(NSMutableArray *)symbols
{

    NSMutableArray * newSymbols = [[NSMutableArray alloc]init];
    NSString * operatorSigns    = @"*/%";
    long result = 0;

    for (int i = 0; i < symbols.count; i++){

        // operand
        if (i%2 == 0){
            [newSymbols addObject:symbols[i]];
        } else { // operator

            if ([operatorSigns containsString:symbols[i]]){
                result = [self calcNumbers:symbols[i] andNumberOne:symbols[i-1] andNumberTwo:symbols[i+1]];
                [newSymbols insertObject:[NSNumber numberWithLong:result] atIndex:i-1];
                i = i + 1;
            } else {
                [newSymbols addObject:symbols[i]];
            }
        }
    }

    for (int i = 0; i < newSymbols.count; i++){
        if (i%2 == 1){
            result = [self calcNumbers:newSymbols[i] andNumberOne:newSymbols[i-1] andNumberTwo:newSymbols[i+1]];
        }
    }

    return result;
}

@end

这是我的班级。我想在命令行中运行RPN计算器。但在calcNumbers方法中，存在EXC_Arithmetic错误。我认为asterisk正在作为（所有）unix_command工作。我怎样才能解决这个问题？提前致谢

Answer 1

我不认为你现在在postFix做的事情是正确的，我甚至不知道你想要做什么。

发生崩溃是因为您要向calcNumbers发送错误值。坏值是指意外顺序的值。

例如，如果myOperator为@"10"且numberTwo为*，则您将进入else分支：

 result = [numberOne integerValue] % [numberTwo integerValue];

你将被划分（计算模数）为零，这将导致崩溃（你不能除以零）。

如何找到问题（不是实际解决方案）：

添加

NSLog(@"Operator %@, operands: %@, %@", myOperator, numberOne, numberTwo);

这应该可以帮助您查看传递给您的函数的值并找到问题。

EXC_ARITHMETIC错误目标C.

1 个答案: