给我一个C++计算后缀表达式的代码

以下是使用栈实现的C语言计算后缀表达式的代码：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>

#define MAX_EXPRESSION_LEN 100

typedef struct stack {
    int top;
    int* array;
} Stack;

Stack* createStack(int capacity) {
    Stack* stack = (Stack*)malloc(sizeof(Stack));
    stack->top = -1;
    stack->array = (int*)malloc(capacity * sizeof(int));
    return stack;
}

int isEmpty(Stack* stack) {
    return stack->top == -1;
}

void push(Stack* stack, int item) {
    stack->array[++stack->top] = item;
}

int pop(Stack* stack) {
    if (isEmpty(stack)) {
        return -1;
    }
    return stack->array[stack->top--];
}

int evaluatePostfix(char* expression) {
    Stack* stack = createStack(strlen(expression));
    int i, num1, num2, result;

    for (i = 0; expression[i]; i++) {
        if (isdigit(expression[i])) {
            push(stack, expression[i] - '0');
        } else {
            num1 = pop(stack);
            num2 = pop(stack);
            switch (expression[i]) {
                case '+':
                    push(stack, num2 + num1);
                    break;
                case '-':
                    push(stack, num2 - num1);
                    break;
                case '*':
                    push(stack, num2 * num1);
                    break;
                case '/':
                    push(stack, num2 / num1);
                    break;
            }
        }
    }

    result = pop(stack);
    free(stack);
    return result;
}

int main() {
    char expression[MAX_EXPRESSION_LEN];
    printf("Enter a postfix expression: ");
    fgets(expression, MAX_EXPRESSION_LEN, stdin);
    printf("Result: %d\n", evaluatePostfix(expression));
    return 0;
}

注意：这个代码只能计算不带括号的后缀表达式，如果要计算带括号的后缀表达式，需要修改代码。