java - 如何修改此代码上的指数和模数功能才能正常工作？

Question

这里的第一个问题，所以我不完全确定正确的方法，但这里是：

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所以，我一直在寻找一些简单的代码来评估动态字​​符串表达式，并在 Study.com 上找到了这个很棒的代码，但由于某种原因，即使所有其他 4 个二进制运算符都是，指数 ^ 和模数 % 运算符也没有注册或工作工作得很好。

因此，如果你们能看一下并就我如何修改它以使其工作提供一些帮助，我将不胜感激。提前致谢！

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一个简单的例子是：如果你要在代码的开头输入一个操作，例如 String[] go = {"1^2"}或String[] go = {"1%2"}并编译，它将分别自动推迟到错误的表达式：1^2或错误的表达式：1%2。

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这是Study.com上的代码：

public static void main(String[] args) {

    String[] go = {"1+2"};
    if (go.length != 1) {
    System.out.println("Usage: java EvaluateExpression \"expression\"");
    System.exit(1);
    }

    try {
    System.out.println(evaluateExpression(go[0]));
    }
    catch (Exception ex) {
    System.out.println("Wrong expression: " + go[0]);
    }
}

public static int evaluateExpression(String expression) {

    Stack<Integer> operandStack = new Stack<>();

    Stack<Character> operatorStack = new Stack<>();

    expression = insertBlanks(expression);

    String[] tokens = expression.split(" ");

    for (String token: tokens) {
    if (token.length() == 0) 
    continue;
    else if (token.charAt(0) == '+' || token.charAt(0) == '-') {

    while (!operatorStack.isEmpty() &&
    (operatorStack.peek() == '+' ||
    operatorStack.peek() == '-' ||
    operatorStack.peek() == '*' ||
    operatorStack.peek() == '^' ||
    operatorStack.peek() == '%' ||
    operatorStack.peek() == '/')) {
        processAnOperator(operandStack, operatorStack);
    }

    operatorStack.push(token.charAt(0));
    }
    else if (token.charAt(0) == '*' || token.charAt(0) == '/') {

    while (!operatorStack.isEmpty() &&
    (operatorStack.peek() == '*' ||
    operatorStack.peek() == '/')) {
    processAnOperator(operandStack, operatorStack);
    }

        operatorStack.push(token.charAt(0));
       }
       else if (token.trim().charAt(0) == '(') {
       operatorStack.push('(');
       }
       else if (token.trim().charAt(0) == ')') {

       while (operatorStack.peek() != '(') {
       processAnOperator(operandStack, operatorStack);
       }
       operatorStack.pop();
       }
       else {

       operandStack.push(new Integer(token));
       }
       }

       while (!operatorStack.isEmpty()) {
       processAnOperator(operandStack, operatorStack);
       }

       return operandStack.pop();
   }

   public static void processAnOperator(Stack<Integer> operandStack, Stack<Character> operatorStack) {
        char op = operatorStack.pop();
        int op1 = operandStack.pop();
        int op2 = operandStack.pop();
        if (op == '+') operandStack.push(op2 + op1);
        else if (op == '-') operandStack.push(op2 - op1);
        else if (op == '*') operandStack.push(op2 * op1);
        else if (op == '/') operandStack.push(op2 / op1);
        else if (op == '^') operandStack.push(op2 ^ op1);
        else if (op == '%') operandStack.push(op2 % op1);
}

public static String insertBlanks(String s) {
    String result = "";
    for (int i = 0; i < s.length(); i++) {
    if (s.charAt(i) == '(' || s.charAt(i) == ')' ||
    s.charAt(i) == '+' || s.charAt(i) == '-' || s.charAt(i) == '^' || s.charAt(i) == '%' ||
    s.charAt(i) == '*' || s.charAt(i) == '/')
    result += " " + s.charAt(i) + " ";
    else
    result += s.charAt(i);
    }
    return result;
}

标签： javaevaloperator-precedencemodulusexponent