算数表达式求值 栈c++

算数表达式求值可以使用栈来实现，以下是一个简单的实现示例：

def evaluate_expression(expression):
    # 定义操作符优先级
    precedence = {'+': 1, '-': 1, '*': 2, '/': 2}

    # 定义操作数栈和操作符栈
    operand_stack = []
    operator_stack = []

    # 辅助函数：执行操作符计算
    def apply_operator():
        operator = operator_stack.pop()
        operand2 = operand_stack.pop()
        operand1 = operand_stack.pop()

        if operator == '+':
            result = operand1 + operand2
        elif operator == '-':
            result = operand1 - operand2
        elif operator == '*':
            result = operand1 * operand2
        elif operator == '/':
            result = operand1 / operand2

        operand_stack.append(result)

    # 遍历表达式计算结果
    for char in expression:
        if char.isdigit():
            operand_stack.append(int(char))
        elif char in ['+', '-', '*', '/']:
            while (operator_stack and operator_stack[-1] != '(' and
                   precedence[char] <= precedence[operator_stack[-1]]):
                apply_operator()
            operator_stack.append(char)
        elif char == '(':
            operator_stack.append(char)
        elif char == ')':
            while operator_stack[-1] != '(':
                apply_operator()
            operator_stack.pop()

    while operator_stack:
        apply_operator()

    return operand_stack[-1]

expression = input("请输入算数表达式: ")
result = evaluate_expression(expression)
print(f"表达式的计算结果为: {result}")

这段代码可以读入一个算术表达式，并使用栈来求值。注意，这里只考虑了简单的四则运算，没有处理复杂的情况如函数调用、括号嵌套等。