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我正在做我的计算器课业。我已经快完成了。

现在，我的计算器可以做例如 2+3+5x6-3/2x6x7-8x9 和 6*9+7

但它不能做到 2*4*8.......

任何人都可以告诉我代码有什么问题吗？这是我在下面的代码：

@实现计算器大脑

- (void)setOperand:(double)aDouble
{
    operand = aDouble;
}


- (double)performOperation:(NSString *)operation
{
    if ([operation isEqual:@"sqrt"]){
        operand = sqrt(operand);
    }
    else if ([@"+/-" isEqual:operation]) {
        operand = - operand;
    }    
    else if ([@"%" isEqual:operation]) {
        operand = operand/ 100;
    }
    else if ([@"1/x" isEqual:operation]) {
        operand = 1/operand;
    }
    else if ([@"C" isEqual:operation]){
        operand = 0;
    }
    else if ([@"AC" isEqual:operation])  {
        operand = 0;
        alwaysFirstDigit = 0;
        digi1 = 0;
        digi2 = 0;

    }else {

        //Assign the first digit to alwaysFirstDigit, and decide the second digit to digi1 or digi2
        if (start == 0){

            alwaysFirstDigit = operand;
            NSLog(@"alwaysFirstDigit = %f", alwaysFirstDigit);

            operationFirst = operation;
            NSLog(@"operationFirst = %@", operationFirst);

            start = 1;

        }else  if (signFlag == 1){
            digi2 = operand;
            NSLog(@"digi2 = %f", digi2);

        }else {
            digi1 = operand;
            NSLog(@"digi1 = %f", digi1);
            }



        // This is an accumulator if first operation is equal to * or /
        if (signFlag == 1) {
        NSLog(@"RUN01 ");


            if ([@"+" isEqual:operationSecond]) 
            {
                digi1 = digi1 + digi2; 
            }
            else if ([@"*" isEqual:operationSecond]) 
            {
                digi1 = digi1 * digi2;
            }
            else if ([@"-" isEqual:operationSecond])
            {
                digi1 = digi1 - digi2;
            }
            else if ([@"/" isEqual:operationSecond]) 
            {
                digi1 = digi1 / digi2;
            }
            digi2 = 0;
            signFlag = 0;
            NSLog(@"This is digi1 in / = %f, %f", digi1, digi2);

        }


        // if operationFirst is = to + or -
        if (([operationFirst isEqual:@"+"]) || ([operationFirst isEqual:@"-"])){  
            NSLog(@"RUN02 ");

        // if operationFirst is = to + or -
            if (([operation isEqual:@"+"]) || ([operation isEqual:@"-"])){

                if ([@"+" isEqual:operationFirst]) 
                {
                    alwaysFirstDigit = alwaysFirstDigit + digi1; 
                }
                else if ([@"-" isEqual:operationFirst]) 
                {
                alwaysFirstDigit = alwaysFirstDigit - digi1;
                }

                operationFirst = operation;  //
                operand = alwaysFirstDigit;  //
            }

            if (([operation isEqual:@"*"]) || ([operation isEqual:@"/"])){
                NSLog(@"RUN03 ");

                signFlag = 1;  //
                operationSecond = operation;  //
                NSLog(@"operationSecond = %@", operationSecond);
            }
        }         


        // it's work
        if (([operationFirst isEqual:@"*"]) || ([operationFirst isEqual:@"/"])){  
            NSLog(@"This is digi1 in *** = %f", alwaysFirstDigit);
            NSLog(@"RUN04 ");

            if (([operation isEqual:@"+"]) || ([operation isEqual:@"-"])){
                NSLog(@"RUN05 ");

                if ([@"*" isEqual:operationFirst]) 
                {
                    alwaysFirstDigit = alwaysFirstDigit * digi1; 
                }
                else if ([@"/" isEqual:operationFirst]) 
                {
                    alwaysFirstDigit = alwaysFirstDigit / digi1;
                }
                operationFirst = operation;  //
                operand = alwaysFirstDigit;  //
            } 

            **// maybe here is the problem !!!!!**
            if (([operation isEqual:@"*"]) || ([operation isEqual:@"/"])){
                NSLog(@"RUN06 ");

                temp1 = digi1;

                operationFirst = operation;  //
                operand = alwaysFirstDigit;  //
            }
        }         


        if([operation isEqual:@"="]){
            NSLog(@"This is temp1 in ***** = %f", temp1);


            if ([@"+" isEqual:operationFirst]) 
            {
                alwaysFirstDigit = alwaysFirstDigit + digi1; 
            }
            else if ([@"*" isEqual:operationFirst]) 
            {
                alwaysFirstDigit = alwaysFirstDigit * digi1;
            }
            else if ([@"-" isEqual:operationFirst])
            {
                alwaysFirstDigit = alwaysFirstDigit - digi1;
            }
            else if ([@"/" isEqual:operationFirst]) 
            {
                alwaysFirstDigit = alwaysFirstDigit / digi1;
            }

                digi1 = 0;
                operand = alwaysFirstDigit;
                operation = @"";
                start = 0;
        }
    }
return operand;
}

@end
4

1 回答 1

0

在您评论的部分下：

 // if operationFirst is = to + or -

if 子句中有一些代码开始：

  if (([operation isEqual:@"*"]) || ([operation isEqual:@"/"])){

这段代码永远不会运行，因为它包含在一个 if 块中，上面写着：

    if (([operationFirst isEqual:@"+"]) || ([operationFirst isEqual:@"-"])){  
        NSLog(@"RUN02 ");

我不知道这是否是你的问题。您可能还想考虑为您尝试实现的计算器语言使用解析器和语法。Alfred Aho 和其他人的《编译器、原理、技术和工具》一书被称为“龙之书”，因为几十年来它的封面上有一条龙，是制作和理解诸如台式计算器之类的语法解析器的传统来源（这是它使用的示例之一），这确实是您要编写的代码。除了为您提供完美的台式计算器语法外，它还将使您对编译器的了解增加很多倍。

于 2012-08-18T20:01:32.743 回答