EXC_ARITHMETIC错误目标C

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。我正尝试在命令行中运行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。我该如何解决这个问题呢？提前感谢

Answer 1

我不认为你现在在postFix中做的是正确的，我甚至不知道你想要做什么。

崩溃的发生是因为您向calcNumbers发送了错误的值。我所说的坏值是指以意想不到的顺序的值。

例如，如果myOperator为@"10"，numberTwo为*，则您将输入else分支：

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

并且您将除以零(计算模数)，这将导致崩溃(您不能除以零)。

如何找到问题(不是实际的解决方案)：

添加

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

这将帮助您查看传递给函数的值，并找到问题所在。