数据结构算术表达式求值具体实现代码

以下是一个简单的数据结构算术表达式求值的具体实现代码，仅供参考：

#include <iostream>
#include <stack>
#include <string>
#include <vector>

using namespace std;

// 定义运算符优先级
int priority(char ch) {
    if (ch == '^') {
        return 3;
    } else if (ch == '*' || ch == '/') {
        return 2;
    } else if (ch == '+' || ch == '-') {
        return 1;
    } else {
        return 0;
    }
}

// 将中缀表达式转换为后缀表达式
vector<string> infix2postfix(string str) {
    stack<char> opStack;
    vector<string> result;
    string temp;
    int length = str.length();

    for (int i = 0; i < length; i++) {
        char ch = str[i];

        if (isdigit(ch)) {
            temp += ch;
        } else if (ch == '.') {
            temp += ch;
        } else if (isalpha(ch)) {
            temp += ch;
        } else if (ch == '(') {
            opStack.push(ch);
        } else if (ch == ')') {
            while (!opStack.empty() && opStack.top() != '(') {
                temp = opStack.top();
                result.push_back(temp);
                opStack.pop();
            }

            if (!opStack.empty() && opStack.top() == '(') {
                opStack.pop();
            }
        } else if (ch == '+' || ch == '-' || ch == '*' || ch == '/' || ch == '^') {
            while (!opStack.empty() && opStack.top() != '(' && priority(ch) <= priority(opStack.top())) {
                temp = opStack.top();
                result.push_back(temp);
                opStack.pop();
            }

            opStack.push(ch);
        }
    }

    while (!opStack.empty()) {
        temp = opStack.top();
        result.push_back(temp);
        opStack.pop();
    }

    return result;
}

// 从后缀表达式中计算结果
float evaluatePostfix(vector<string> postfix) {
    stack<float> stack;
    int length = postfix.size();

    for (int i = 0; i < length; i++) {
        string token = postfix[i];

        if (isdigit(token[0])) {
            float number = stof(token);
            stack.push(number);
        } else if (token == "+" || token == "-" || token == "*" || token == "/" || token == "^") {
            float operand2 = stack.top();
            stack.pop();
            float operand1 = stack.top();
            stack.pop();
            float result = 0;

            if (token == "+") {
                result = operand1 + operand2;
            } else if (token == "-") {
                result = operand1 - operand2;
            } else if (token == "*") {
                result = operand1 * operand2;
            } else if (token == "/") {
                result = operand1 / operand2;
            } else if (token == "^") {
                result = pow(operand1, operand2);
            }

            stack.push(result);
        }
    }

    return stack.top();
}

int main() {
    string str;

    cout << "请输入一个中缀表达式：";
    cin >> str;

    vector<string> postfix = infix2postfix(str);
    float result = evaluatePostfix(postfix);

    cout << "计算结果为：" << result << endl;
    return 0;
}